WATCH: Systems of Exchange and Trade

CRAIG BENJAMIN: Hello. I'm standing here at the Port of Seattle, one of the great commercial ports of the world, as a reminder to all of us that we live today at the center of this vast, connected, globalized world. But, of course, to a certain extent, it's always been this way. From the beginning of human history, our early cultures, early civilizations have been connected in various ways. We fought with each other, we traded ideas with each other, we traded material goods with each other, we traded diseases with each other. This is particularly true during the era of agrarian civilizations, when these vast civilizations that appeared in the Afro-Eurasian world zone established conditions that were right for scales of exchange hitherto unseen in human history. The key players in this were the Romans, the Parthians, the Kushans, and the Han Chinese. And with the road networks they laid down, with the port facilities they constructed, with the coinage they started to use, conditions were ready for trade that we had not seen before. This happened mainly along the great Silk Roads network. This is a network of roads that connected China through Central Asia, joining the mountain ranges of Central Asia and the deserts eventually with the Persian world and onto the Roman world. The Silk Roads exploded in the first century BCE when the Han Chinese began to connect with the rest of Eurasia for the first time. This fortunately coincided with the establishment of more peaceful conditions in Rome with the advent of Augustus, the first emperor of Rome. After a century of civil war, suddenly a climate of peace emerged within Rome that allowed for a demand for exotic goods from Asia to emerge. And what was most in demand was silk. This exotic material spun from these small cocoons spun by worms. In China, the Chinese had discovered this secret thousands of years earlier but now the demand emerged in Rome amongst wealthy patrician women, who came to believe that their most luxurious garments had to be made of this exotic, sensual, translucent material. To supply this demand, caravans would come out of China, cross these dreadful deserts, the Taklamakan, the Gobi desert, crossed the highest mountain ranges on Earth, passing these goods onto various middlemen along the way until they ended up in China. Maritime routes became important too as more and more port facilities were developed, as sailors discovered the monsoon trade winds that would drive the ships across the Indian Ocean at one time of the year and then back again the other way at a different time of the year, this made deep oceangoing transport and trade possible, the sort of thing we see behind me here today. Eventually, these intense levels of trade, which also facilitated the movement of religions and of diseases, began to dissipate in the third century when political instability in Rome and in China brought an end to this great Silk Roads era. Other trade networks existed as well, in Australia, in the Americas. Indeed in the Americas we know that trade was going on between South America, Mesoamerica, and even up into the Ohio Valley, the Mississippi Valley, Chaco Canyon, and so on. We have evidence of plenty of goods and crops moving back and forth. But frankly, the scales of exchange in these other parts of the world was so much smaller, so much less intense. This gave Afro-Eurasia something of an edge. It became more dynamic, it had larger populations, it had people who built up immunities to diseases, it had a lot more technological sophistication. So when the world zones began to reconnect after 1492, Afro-Eurasia was said to absolutely dominate these other world zones and drive the world into the modern revolution. In many ways, the Silk Roads were the forerunner to the sort of scales of exchanges you see behind me now. This was the beginning of the establishment of these great global trade networks.