Silk, Silver and Ideas
1Long before money, people traded by barter, exchanging one good directly for another. A herder might trade a goat for a farmer's grain. Barter works well when each side wants what the other has. But a potter who wants fish must find a fisher who happens to want pots, and a cow cannot be split to pay for something small.
2Over time, many peoples used goods such as grain, cattle, cowrie shells or weighed lumps of metal to measure value. About 600 BCE, rulers of Lydia, a kingdom in what is now western Turkey, began stamping small lumps of electrum, a mix of gold and silver, with a royal lion's head. The stamp showed that each coin had a set weight, so traders did not have to weigh metal at every sale. Greek cities soon made coins of their own. In China, people used bronze coins shaped like small tools, and after China was united in 221 BCE, round bronze coins with a square hole became standard.
3About 125 BCE, a Chinese envoy named Zhang Qian returned from a long journey to Central Asia and told the Han emperor about the kingdoms and goods to the west. Trade along the routes grew. Historians call these routes the Silk Roads, though they were not one road, and silk was only one of many goods.
4Around 100 CE, a merchant in Chang'an might buy bolts of silk and bronze mirrors with bronze coins. His camels carried them to Dunhuang, where he sold them to a Sogdian merchant from Samarkand for silver coins and two Central Asian horses, which were prized in China. At Kashgar, the Sogdian traded a bolt of silk for food and water for his camels. In Samarkand he sold the rest to Parthian merchants from Persia, who carried it west to Antioch. There a Roman trader paid in gold coins. Each merchant charged more than he had paid, and cities collected taxes along the way, so silk in Rome cost many times its price in Chang'an.
5The routes carried ideas as well as goods. Roman glassware and coins moved east, and Buddhist monks from India carried their teachings north through Kashgar and Dunhuang into China, where Buddhism had taken root by the first century CE. Archaeologists have found Roman coins in southern India and pieces of Chinese silk in tombs at Palmyra, in Syria.