I. Searching for roots of the Silk Road: dangers of retrospective interpretation.

A. "Silk roads" forever-the mummies, cowrie shells, the Pazyryk rug, etc.
B. Were the Chinese searching for distant markets?
C. Were the nomads coveting Chinese products?

II. What was going on to the north and west of China?

A. Our knowledge of the early nomads-the evidence of archaeology.
B. The steppe vs. the sown or the steppe and the sown.
C. The early Chinese walls as evidence of offensive, not defensive strategies.

III. Writing and re-writing the history of what happened: Ssu-ma Ch'ien (ca. 145-ca. 85 BCE) and Pan Ku (ca.32-92 CE).

IV. The rise and fall of the Xiongnu (Hsiung-nu).

A. Strength matches strength (Barfield) or a more nuanced interpretation (Di Cosmo)?
B. Mao-tun (209-174 BCE) responds to the Qin offensive.
C. Structure of empire; strength and weakness of imperial power.
D. Civil war (58 BCE).

V. Evolution of Chinese-nomad interaction.

A. The ho-ch'in treaty arrangements, a concession to the nomads' superior force.
B. Why "appeasement" failed.
C. Han emperor Wu-ti (141-87 BCE) goes on the offensive.

1. Zhang Qian's (Chang Ch'ien's) missions to the West; how they were remembered.
2. The "Heavenly Horses."
3. Military campaigns.

C. Establishment of the Han protectorate in the Tarim basin (ca. 60 BCE); the fortifications near Dunhuang.
D. The meaning of the "new" tributary status of the Xiongnu beginning in 53 BCE.
E. The last assertions of both Xiongnu and Han strength in the first century CE.

VI. A cost/benefit analysis: The importance of stability for both the Chinese and the nomads.

From Barfield, Perilous Frontier, pp. 56-57, on costs of wars vs. Xiongnu:

Victories, as well as defeats, cost the Han heavily. The campaigns of 125-24 BC, in which 19,000 Hsiung-nu and a million sheep were reported captures, cost the government 200,000 chin of gold in rewards to the generals and troops, and the loss of 100,000 horses. The surrender of the Hun-yeh king was induced partially by an expenditure of 10 billion cash in gifts and food to the surrendered leader and his people. (One chin of gold = 244 g and was officially valued at 10,000 cash.) The great Han victory of 119 BC cost tens of thousands of Han dead, 100,000 lost horses, and 500,000 chin in gold as rewards. These figures did not include the enormous cost of supplying the army on the steppe with provisions. Li Kuang-li lost 80 percent of his men during the first abortive attack on Ta-yüan [Ferghana in today's Uzbekistan-DW] in 104 BC, mostly through mismanagement of supplies. In his successful second attempt, only 30,000 men reached Ta-yüan out of an initial force of 180,000.

Gifts to the Xiongnu ruler when he came to the Han court (source: Barfield, Perilous Frontier, p. 65):

year of visit	silk floss	silk fabric
51 BCE	6,000 chin	8,000 pieces
49 BCE	8,000 chin	9,000 pieces
33 BCE	16,000 chin	16,000 pieces
25 BCE	20,000 chin	20,000 pieces
1 BCE	30,000 chin	30,000 pieces

References:
Thomas Barfield
The Perilous Frontier: Nomadic Empires and China, 221 BC to AD 1757 (Blackwell, 1989; pb. ed., 1992).
Nicola Di Cosmo
Ancient China and its Enemies: The Rise of Nomadic Power in East Asian History (Cambridge Univ. Pr., 2002).