within recent years before and after 1500 BCE. Trade networks reached north to Oasisamerica. There is evidence of established maritime trade with the cultures of northwestern South America and the Caribbean. Middle Ages During the Middle Ages, commerce developed in Europe by trading luxury goods at trade fairs. Wealth became converted into movable wealth or capital. Banking systems developed where money on account was transferred across national boundaries. Hand to hand markets became a feature of town life and were regulated by town authorities. Western Europe established a complex and expansive trade network with cargo ships being the main carrier of goods; Cogs and Hulks are two examples of such cargo ships. Many ports would develop their own extensive trade networks. The English port city of Bristol traded with peoples from what is modern day Iceland, all along the western coast of France, and down to what is now Spain. During the Middle Ages, Central Asia was the economic center of the world. The Sogdians dominated the east–west trade route known as the Silk Road after the 4th century CE up to the 8th century CE, with Suyab and Talas ranking among their main centers in the north. They were the main caravan merchants of Central Asia. From the Middle Ages, the maritime republics, in particular Venice, Pisa and Genoa, played a key role in trade along the Mediterranean. From the 11th to the late 15th centuries, the Venetian Republic and the Republic of Genoa were major trade centers. They dominated trade in the Mediterranean and the Black Sea, having the monopoly between Europe and the Near East for centuries. From the 8th to the 11th century, the Vikings and Varangians traded as they sailed from and to Scandinavia. Vikings sailed to Western Europe, while Varangians to Russia. The Hanseatic League was an alliance of trading cities that maintained a trade monopoly over most of Northern Europe and the Baltic, between the 13th and 17th centuries. The Age of Sail and the Industrial Revolution Portuguese explorer Vasco da Gama pioneered the European spice trade in 1498 when he reached Calicut after sailing around the Cape of Good Hope at the southern tip of the African continent. Prior to this, the flow of spice into Europe from India was controlled by Islamic powers, especially Egypt. The spice trade was of major economic importance and helped spur the Age of Discovery in