In the fourth century, the Persians drastically raised the price of raw silk they sold to the Byzantine merchants. Justinian, the Byzantine ruler, attempted to prevent serious consequences to his kingdom's balance of trade:

"Justinian forbade the sale of silk at more than eight chrysos a pound -- an absurd and impracticable measure, this price being below that which the merchants had to pay. Consequently, they were no longer willing to undertake this form of trade. They hastened to sell off their remaining stock. . . . In the towns, all those who had devoted themselves to the silk trade were reduced to beggary; craftsmen and labourers finished up in poverty. Many of them emigrated and went to take refuge among the Persians."

-- Procopius of Caesarea, circa A.D. 420-440

Reprinted by permission of the following. Part 1: La Route de La Soie, Luce Boulonois, Editions Arthaud, 1964; Part 2: The Shorter Pepys, edited by Robert Latham, University of California Press, 1985; Part 3: The Wheels of Commerce, Fernand Braudel, Librairie Armand Colin, Paris, 1979. English translation copyright 1982 by William Collins Sons Ltd. and Harper & Row Publishers Inc., 1982. Reprinted by permission of Harper & Row; Part 4: Thomas Jefferson: Writings, edited by Merrill D. Peterson, The Library of America, 1986