George Modelski William R Thompson

University of Washington Indiana University

Seattle WA 98195 Bloomigton IN 47405


Paper to be presented at the 37th convention of the

International Studies Association at San Diego,

April 16-20, 1996.





This paper poses the following questions about the operation of the world economy:


1. can we demonstrate the existence of major pulses in the form of an alternation between periods of core concentration, followed by deconcentration by way of diffusion, trade and migrations, and lasting about a millennium each, and show them to have shaped world economic development since the fourth millennium BC?

2. can such pulses, if they exist, also be shown to coevolve in tandem with major world cultural, and social, processes, including the spread of writing, urbanization and migration?

3. what might be the explanation for such major processes?


Our inquiry takes off from our recent work on the rise and decline of leading sectors in the global economy, and on how a succession of such leading sectors over the long period of the last millennium has not only shaped the evolution of the global economy but has also paced the rise and decline of world powers and therefore the major structural features of global politics (Modelski and Thompson 1996). The hallmark of that work was explicit theorizing, and empirical documentation and testing of our propositions. We are now extending that type of analysis back in time, working with a longer time span but again looking for innovative changes that produce structural transformations.

But our inquiry is not moving into waters that are entirely uncharted. In our earlier work we did see the rise and decline of leading sectors as "processes that are nested within the larger framework of the evolution of the world economy" (ib., p.123), and did in fact propose in Chapter 8 and in Table 8.1, a broad time-structure for this world economy process. We are now seeking empirical confirmation for it in respect of its earlier stages. That means that we shall be looking primarily at the evidence from the time prior to the year 1000, and that is for the period roughly between -3500 and +1000. Most generally, we are operating with a conception of "world system evolution" (Modelski 1995).

In a more general sense, though, the territory we are entering is indeed uncharted. We know of no text or canonical treatment of the history of world economy against which we could test our analysis. Most economic histories do not extend much beyond the industrial revolution or the rise of the modern world and there is no theory of economic change in the world economy. General world histories treat of economic matters only in an incidental fashion. There is indeed a debate on record, the so-called "ancient economy" debate (Frank 1993:385-6), questioning whether and to what extent markets, capital accumulation and long-distance trade were of any importance in pre-modern conditions.

Our own position maintains, with John Hicks (A THEORY OF ECONOMIC HISTORY 1969) that the economic history of the world can be treated as a single process. Hicks saw that process, in broad terms, as a movement toward a market economy, and that is a serviceable conception, but his account was not fleshed out in detail, with reference to particular economies, or with the support of other empirical or systematic data. In other words, much remains to be done in this important field.


World economy process

Our key concept is the "world economy process" defined as the process by which a world economy is created and transformed, and our basic premise is that the human species has "world economy potential", that is that in favorable conditions a world economy might arise.World economy is one of the (four) dimensions of the world system, concerned with the production and consumption arrangements of that system, such as firms and markets. It is a recent theoretical construct that directs our attention to certain arrangements, and the arrangements it illuminates become sharply visible only with a certain effort on the part of the observer, especially in earlier periods. We do not posit the "existence" of a fully-fledged world economy in -3500; only the possibility that developments around that time set in motion a continuous process whose more recent forms look increasingly like a world economy /1/.We stress the continuity of that process: in our model we conceive a single line of descent linking economic practices in Mesopotamia with those in the contemporary world. We share with Frank (1991) a concern for demonstrating that continuity, but we do not assume such a continuity to be evident in a purely linear form in which the only change variable is measured along a "prosperity-depression" axis, as though the only change that mattered was the size and variability of general output or gross product.  /2/ Rather we intend to show that over such long periods (we shall deal with periods of one thousand years at a time, just as, in our earlier study, we analyzed periods of one half-century) a measure of orderly phasing might be discerned, in which qualitative and structural change is of the essence. Our primary task , therefore, is not to map "the geographical extent of the world system" (Frank 1993:383) and, a fortiori, of the world economy, or the "spatial scale of integration, esp. by trade" (Chase-Dunn and Hall 1995:116). That is, of course, a very useful datum, and it is always worthwhile to be able to chart the degree to which the actual world economy might approximate the potential (species-wide) world economy, and how that extent changes. For instance, Colin McEvedy's maps in THE PENGUIN ATLAS OF ANCIENT HISTORY (1967), say for 2750 BC, (p.23), and for 1850 BC (p.29) show the limits of copper working, and for the latter map, also for bronze working, and in effect display, in an attractive manner, the extent of the world economy at those two points in time. But the limits he shows may not be entirely conclusive, and may not show all the trading links and other connections extant at those points in time. In recent writing the problem of "incorporation" has tended to be given a rather restrictive reading, making it appear as though large parts of the world, e.g. China, had become participants in the world economy only since the mid-19th century. That is manifestly wrong; in our view, the onus in such matters is on those wishing to prove lack of "incorporation" rather than the other way around. Our suspicion is that our studies tend to underestimate the actual degree of the interdependence of the human species. We do not minimize interdependence but are much impressed with the practical difficulties in reliably portraying networks.  Our search is not for descriptions of networks, but for the laws that govern their transformations.

Core concentration and dispersal

Our model distinguishes six periods of the world economy, as follows: I (Sumer-Egypt) -3500 - -2400; II Fertile Crescent -2400 - -1200; III ("Iron" cores) -1200 - -100 ; IV Silk Roads -100 - 930; V Market Economy -930- 1850, and VI  World Market from 1850 onward (after Modelski and Thompson 1996:125). Some of these labels are provisional. Maybe we need other labels to capture the most important characteristics of this processes but the basically conventional labels we have been using are not really entirely serviceable. In particular those of Bronze and Iron ages, bestowed upon us by 19th century archaeologists for whom metal objects were among the best preserved traces of early human activity, are inaccurate. The labels themselves are of some antiquity, and go back to the time of the transition from bronze to iron. Hesiod (ca. -700) wrote of a Golden age in the remote past, that was then followed by a silver age, a bronze age, and an iron age, and he considered the last to be less civilized than the bronze that went before it.  (Whitrow 1988:48-9) What is not clear is whether bronze and iron manufactures, in their time, constituted significant sectors of the world economy, or whether their primary meaning was in marking off changes in military and weapons technology, hence impacting forms of political organization. While bronze first appears in Sumer soon after -3000, it does not reach Egypt until much later and on McEvedy's (1967) maps Egypt does not appear in the bronze-working areas until -1850. Nor is accuracy served by labeling the subsequent period as "iron" when iron remains one of the basic materials of the economy to this day.


The following questions now arise:

1. What is the evidence that might support such a periodization in respect of the first four periods (I-IV), one that focuses in on structural transformations marked by these period?

2. What might be the support for the claim that periods I and III (of about a millennium in length each ) might best be described as processes of core formation, and the second set (periods II and IV, of about the same length) as periods of deconcentration, or amalgamations.


These six periods might in turn be compressed into three major eras, being those of the Ancient, the Classical, and the Modern worlds and each of them may be distinguished by its principal demographic characteristics, (after McEvedy and Jones 1979), as follows:

World population Mid-range (range)(m) (m) Neolithic (-10000 - -4000) 4-7 5 Ancient (-3500 - -1200) 10 - 50 25 Classic (-1200 - 930) 50 - 250 150 Modern (930 - 250 -(12,000) 6,000

This is to establish that both the Ancient, the Classic and the Modern eras are distinguished by the size of their populations, that determined i.a. the size of their markets, and the maximum degree of specialization. Our next point is that within each of the two eras we are discussing, the Ancient (Bronze age), and the Classic, two distinct phases may be distinguished, those of nuclei, and those of amalgamations, and especially so if we begin by focussing our attention on the core areas. We claim that we establish in the world economy, on the scale of a millennium, the existence of pulsations that first create nuclei of economic productivity and growth and then, in the next millennium, amalgamate the nuclei and spread the goods around. Our thesis inverts the Chase-Dunn and Hall (1995:116) proposal that "all world-systems pulsate in the sense that their spatial scale of integration, esp. by trade, gets larger, and then smaller again". In our sequence, nuclei consolidate first (as in Sumer, and in Egypt) and then amalgamate and thin out, and spread their effect to Indus, Europe, and China; in the next pulsation, we have four great regional centers first nucleate in China, India,the Near East, and finally the Mediterranean, and then amalgamate, albeit in a loose fashion, via trade routes.

Ancient world

For the first, the Ancient era, the initial  "active zone" is found in southern Mesopotamia, and is centered on Sumer. Its economic base is irrigation agriculture, but it is also the first time that cities emerge in world history, and not just one city but a system of autonomous cities; indeed, Gordon Childe (1936, Ch.6; cf. also Adams 1966:4) termed this the "Urban Revolution". The prominent early city was probably Uruk,  (in particular in the protoliterate period -3700 - -2900) /3/. Uruk is the central locale of the epic of Gilgamesh but the founding myth in that epic is one of Seven Sages who brought civilization to seven of the oldest cities /4/. Initially these were urban communities centered on a temple precinct, but in time, ca. -2700, walls appear and palaces for rulers. Gilgamesh, the hero, built the ramparts of Uruk, and archeologists claim the wall of Uruk to have been six miles in circumference. Such an area could have accommodated several tens of thousands of people. The estimated population of Sumer ca.-3000 is thought to have been about one million, and had shown, in the preceding millennium a tremendous growth factor of 10 (from 100,000 to 1m) (McEvedy and Jones 1979:149). The one comparable area, in a counterpoint to Sumer, was that of Egypt, initially believed to be influenced by Sumer, but soon launched on its own developmental path whose main characteristic was not a system of city states but political unification, after -3100, into one state, with a capital at Memphis.

Egypt's population, ca. -3000, was about that of the Sumerian system, on the one million mark. Egypt seems to have borrowed from Sumerian pictograms, and lagged in bronze, and in wheeled vehicles, but it not only produced magnificent stone structures but also originated the calendar, one of 12 months and 30 days, that is still in use. It would seem that world civilization may have originated not so much in a single nucleus but in a bifocal configuration, exhibiting a tension between a freewheeling, multiple-player city system, and a more ordered, unified, quasi-imperial mode. Our Table 1 presents data on the world distribution of cities in the Ancient era ending -1200. The table is based on Tertius Chandler's (1987) census of the most populous cities in the world that starts in -2250 and ends in the 20th century. We value the Chandler data for its systematic coverage and long time span, and take it as a starting point of our analysis (for a critical appraisal see Wilkinson 1991), but we also supplement it with a list of early Sumerian cities, and thus extend it back to -3500.


Two main points emerge from this data. First, for the early part (I), the principal area of the urban revolution is Sumer. Here we have a system of cities that on the basis of irrigation agriculture, in itself a major innovation, forms the matrix  from which spring a series of other clusters of innovation, most importantly the city system itself, and also writing, pottery and bronze working, ships, and possibly markets. /5/ Second, (II), by mid-third millennium, and until - 1200, the system of cities spreads through the Fertile Crescent, linking Mesopotamia to Egypt, but also enters the Indus Valley, Europe (Knossos, and then Mycenae), and finally also China, in the Shang period that brought bronze. Whether China received urban civilization from the west via the steppes is in dispute. /6/ But the context suggests it might have, and in particular the location of first Chinese urban areas, and all its capitals, on the upper reaches of the Yellow river system, facing the steppes; our knowledge that through most of Chinese history the challenges came from the steppes; and finally the shape of the temporal dispersion of the city system, the urban revolution reaching China (being the furthest away) only at the end of this era. We might say that the human species thus learnt to live in cities, and learnt all those special skills that living in cities required and made possible. If the spread of cities was the initial learning process the city being mankind's first major cultural artifact, then it not only carried with it the basic innovations of the Sumerians such as literacy, irrigation, construction, metal working and craftsmanship but also benefited from other, subsequent innovations that appeared to facilitate that dispersion. We might describe the spread of cities as fitting a learning curve. We might also think here of such innovations as the horse-drawn chariot, caravan trade (with recently domesticated camels), and regular shipping (e.g. from Ur whose ruler was described as the "sea king" and his trade route to the Indus Valley, as the oldest authenticated trade route). This was not the beginning of trade; exchange of goods is certainly more ancient than that, and long-range trade routes (e.g. across Siberia) probably go back to the end of the last ice age. Kohl"s (1978) presents the trading system as it was ca. -2500. But new methods of commercial organization and a higher level of exchange may be identified with the Fertile Crescent period of the ancient world.

Classical world

The end of the bronze age is now commonly situated at around -1200. Robert Drews' (1993) work is a crisp account of that "catastrophe" that overtook numerous cities in the Eastern Mediterranean at about that time, an outcome that he attributes to a politico-military factor, to the superiority of the foot soldiers armed with iron "cut-and-thrust" swords over the chariot armies of the later Bronze age /7/. Let us open this discussion by looking at data on population trends in the classical world (Table 2) and propose once again that this period,too, might be seen, in its economic aspects, in a double-beat perspective. The population data, an order of magnitude greater than in the ancient world, show a process in two phases. In the first, we see rapid agricultural development (linked in part to the iron plough) as indicated by high population growth, in the all the chief regions of the old world:  tremendous expansion in China, especially in the Yellow River valley, but beginning to spill into the Yangtse valley too, and producing a eight-fold population increase in about one thousand years; similarly strong growth in India, this time in the Ganges valley, as well as a tripling of population in Europe, from the colonization of the Mediterranean basin, and linked to notable trading activities. World population increases from 50 to 170 in one millennium, a growth factor of 3.4. Such growth, largely expansion in previously unused land, but also aided by an increase in urbanization, creates a Eurasia-wide core area of major substance.Table 2 about here)Contrast this period with what follows, roughly in the next millennium (-100 to 930). World population does rise, but only by a factor of 1.5. China's population gains only slightly, and so does that of Europe, and Near East. Only India sees a doubling in its numbers. The degree of urbanization (as indicated by the proportion of population living in the top-25 world cities) remains constant. /8/ In other words, a period of core expansion is followed by one of growth deceleration, and in parts, of deconcentration. These are of course, in Europe, the dark ages attributable to the decline and fall of the Roman Empire, in China, the times of trouble following the collapse of Han, and  the dissolution of T'ang, and in the Northwest of India, the disappearance of the Kushan Empire.


By contrast with core concentration, and with basically a stable level of economic activity in the first, we can observe in the second period, a rising volume of long-distance trade. The backbone of those exchanges extending over the whole of Eurasia is the so-called Silk road, both in its maritime and its overland variants. The onset might be dated from the arrival of Han troops in Central Asia, just before -100, and the Silk Roads continue in business well into the modern era. At about 900, most of the top-25 cities in the world are linked with each other by that system, either by sea or by land. In both versions, Buddhist linkages are particularly active in promoting such contacts, and including trade. Overland, Buddhist monasteries dot the trade routes; over the seas, Buddhist influences spread as far as Java and Indochina (Cambodia, Champa), and in both versions influence developments in China and Japan. The spread of Islam makes the Near East into a central arena of world trade. We might argue too that in the first period, (III), that of core concentration, the dominant innovations facilitated core concentration. Among these me might name are iron metallurgy, and its effects on work productivity, construction and public works, such as roads and canals, opening new areas to settlement, new products such as silk, and coinage, facilitating markets. Figure 1 illustrates the diffusion of the predominance of iron technology over bronze after -1100.

(Figure 1 about here) In the silk road period, (IV), innovations seemed to favor trade and dispersion. The spread of Buddhism (and its monasteries,) and of Islam (and the practice of pilgrimage to Mecca) seem to further long-distance contacts, and so does what appears to be a regular alternation in the maximum exploitation of the silk roads as between the overland and the maritime branches.

Writing, urbanization, great migrations, and the world economy

In other words, our evidence does support the assertion that a structural pattern of temporality appears to characterize the experience of the world economy process in the ancient and classical worlds. Might this pattern be related to other processes, and in particular might it match and synchronize with the other major cultural and social processes?Let us first display our data on the diffusion of writing. We regard the introduction of writing as a major evolutionary phase in the construction of the world system and would expect it to be coevolving with major economic processes.

Figure 2 shows writing to be spreading basically in two major pulses. The first pulse began in Sumer, in pictographic form, and dispersed from there in a pattern broadly matching the spread of cities, as in Table 1, in Mesopotamia, Egypt, Europe, India and China. The second major wave appears to be that of alphabetic writing; it centers on Phoenicia and Greece, and diffuses to Europe, and India, but not to China. These two major pulses match those of the world economy.igure 2 about here)Turning to urbanization, a world social process, the answer is already at hand, and it is positive. We have used information on cities (and populations) as proxies for economic development because systematic data is not available for these early periods. But cities are more than just ensembles of economic activity (or, for that matter, bases for political institutions);  they are in an important sense a new form of social organization, and communities of a new kind. They need to be treated as social structures, and changes in urbanization must be seen as major social processes.Our data (as in Tables 1 and 2) show two distinct pulses of urban growth in the active zones, followed by slower growth or retreat in the active zones, and dispersion of activity elsewh ere in the world system. Urbanization has been a key element of the process of economic concentration and deconcentration. But urban growth also involves much migration. Cities everywhere depend on a steady influx of people from rural areas, and from other cities, and to that extent all urbanization has also been linked to population movements.Some population movements nevertheless stand out for special attention, and we might call them "great migrations", as those that have left their imprint on historical memory. The paradigmatic case of "great migration" is the movement of tribes that brought about the fall of Western Rome, ca. 300-500, but there are others we know about, and they to seem constitute events that punctuate world history. History text regularly refer to them in particular contexts but there is no standard list of such events. However, an archaeologist, E.N. Chernykh (1991:302-9) who regards them as "universal movements" linked to fundamental cultural innovations did recently put together such a list of great migrations across millennia, and we reproduce the essentials of his listing in the left-hand column of Table 3. /9/. Chernykh was puzzled, moreover, by the observed a periodicity in these movements, and proposed the question: what might "explain the specific periodicity of the rhythmic pattern observed"?


On a larger view, urbanization and "great migrations" might be seen as two aspects of one process of social change in the world  system, the long-term problem of building a world community. We might call this the "center-hinterland (C-H) process" (Modelski 1995:18) because that process embodies a lasting tension between pressures for innovation (and therefore change), and the equally important demands for greater equality that are the operating requirement of every community. Innovation, including economic innovation, produces concentrations of urban power where the peaks of social prestige systems are located. But that is also when opulent cities and even powerful empires become  targets for those in the hinterlands who at long but apparently regular intervals mobilize the margins of civilized society for effecting a systemic leveling.

Let us propose that the C-H process consists of successive phases of concentration and deconcentration. The concentration takes the form of urban building, innovations, and investment in productive activities and the social infrastructure. This is then followed by deconcentration during which some cities or industries might be destroyed, and the growth of others retarded, and urban areas be overrun in the course of great migrations, in the consequence of which innovations diffuse, accumulated wealth disperses, and new communities are drawn into these "universal movements".Let us call these C-H phases, for the ancient and classical periods, those of Core Concentration, Dispersal, Reconcentration, and Deconcentration, and assign them to the same periods that we assigned to the world economy process, as above, and in Table 3. We can then ask: do the known phases of urban concentration, and of Chernykh's migrations, correspond, respectively to periods of concentration and deconcentration in the C-H process, and the short answer is, yes, broadly. Indeed, each migration, including the first, appears as a precondition of concentration in the next phase, and each concentration presents opportunities for deconcentration. This might not be the whole picture; we need to study the migrations more closely, and the political and cultural factors would also have be brought in, but as an initial approximation the correspondences seem quite good. The world economy process appears to coevolve with the C-H process:  the world economy changes (albeit quite slowly) in synchrony  with the world social context.

An evolutionary explanation

What might therefore be the answer to our last question, about explanation? What also might be the answer to Chernykh's question about the apparent periodicity of these pulses? Our short answer is that all three of these, the world economy,  world culture, and the center-periphery system, are subject to evolutionary, and coevolutionary, processes.That is, these are processes in which the world system undergoes change in a time-patterned manner. The pattern is that of an evolutionary algorithm: as economic trial and error experiments unfold in favorable conditions, , such as the Sumerian one with irrigation and cities, some succeed, establish themselves, and diffuse over large areas, comprising nuclei of change. Spreading widely, they are tested by selection pressures, both natural (e.g. climate) and social (e.g.migrations) that eliminate some (the Indus valley) and favor others (the Yangtse valley), and gradually consolidate into larger systems. And then new experiments begin. All the while these economic processes  coevolve with changes in culture and in center-hinterland relations. The specific periodicity of these patterns, the long phases of the economic process, and the much longer one of social and cultural process may be understood as resulting from the pressures of synchronization.

The pay-off is this: if we understand the patterning of the earlier processes, we are in a better position to analyze and make predictions about, more contemporary issues. An evolutionary pattern is likely to repeat, and we have reason to believe that the same pattern of concentration and deconcentration is continuing to operate, and that in the modern world we have recently entered another phase of deconcentration and dispersal in the world economy , namely the phase of the world market.



1. We need more discussion of the concept of world economy (cf. Wilkinson 1995:63-68).

2. We leave aside, for the time being, the question of economic pulsations of a period shorter than one thousand years, such as the 250-year periodicities discussed in Gills and Frank 1992.

3. In Mesopotamian archaeology, the "protoliterate" period is dated -3700 - -2900, and "early dynastic", 2900-2400 (Adams 1966:25). In Egyptian history, the "pre-dynastic" (to -3100) was followed by the "early dynastic" period (ca.-3100 to -2686); the Great Pyramids date to about -2500.

4. See Pritchard 1959:40; another Sumerian epic that deals with the beginning of the world refers to the founding of five cities (Jacobsen 1939:58).

5. The Epic of Gilgamesh refers to Uruk not just as "ramparted" but also as "broad-marted" and possibly as "Market-of-the Land". Uruk is described as comprised of three "sar" (city, orchard, and marginal land" (claypits?)and the temple precinct. The epic also describes the construction of a six-decked ship, to cope with an anticipated flood (Pritchard 1959:49,50,67).

6. According to Robert McC. Adams (1966:23) China's "late" civilizational "development increases the likelihood that it may be 'secondary' rather than 'pristine' in significant ways". Chang (1986:414) regards this question "whether ancient Chinese civilization was indeed indigenous or pristine" as simplistic and sees the civilization that arose in Bronze Age China as the product of a fusion of local cultures and as a pattern that is comparable in particular to Mesoamerican ones.

7. According to Drews (1993:75), citing Jane Waldbaum, the distribution of weapons recovered in the Eastern Mediterranean is as follows: 12th cen. contexts, bronze 96 %, iron 3%; 11th cent. " 80 " 2010th cent. " 46 " 54.

8. The degree of urbanization might be estimated by calculating the share of the top-25 world cities in the world population (on the basis of the Chandler data). That works out at about 2 per cent at -500, and in 900, as compared with an estimated 1 per cent in the ancient world (for the Chandler cities in Table 1).

9. On migrations as alleged "causes" of the catastrophe of -1200, see Drews(1995:Ch.4); Drews criticizes the thesis of the migration of the Sea Peoples that he attributes to Gaston Maspero and Edouard Meyer, and finds no evidence for it.