Our general image of ancient civilizations is formed by the great agricultural empires of Eurasia. Nomadic pastoralists are most often regarded as predators to the sedentary-agricultural societies. Histories of many modern countries, however, not only retain signs of conflicts with the encroaching nomads, but also of "barbarian" impact on their culture. The interactions and interdependence between nomads and agriculturalists is an important topic of world history. Our knowledge of the phenomenon, though, is very much hindered by the dearth of information on nomads, especially those in early history, who left few literary sources and often very shallow archaeological remains for historians to explore. Luckily, neighboring sedentary societies did provide information about them, as those agricultural empires or states constantly engaged in military conflicts as well as diplomatic, commercial, marital, and other interactions with them. The Yuezhi people, who early resided near the border of the agricultural part of China and later migrated on the Eurasian steppe all the way to north India, eventually becoming the rulers of the vast agricultural-trading Kushan empire, comprised one of the nomadic groups better known by the sedentary societies of that time. Thus, to trace the migration and settlement of the Yuezhi-Kushan people may be productive in understanding the contributions of nomadic people to world civilizations, or more specifically, the civilizations of China, India, the Eurasian steppe, and to a certain extent, that of West Asia and Europe.

An easy approach to studying the phenomenon of interdependence of nomads and sedentary societies is to examine the modern societies that emerged from ancient civilizations. Nowadays, the first stop of many tourists to China after their arrival at Beijing is often the Great Wall, so close to the capital of modern and medieval China; it is only a short drive to the ancient demarcation of agricultural lands from those of nomads. As a matter of fact, the very location of the capital was determined by the two different ecological zones. Similarly, in South Asia, in particular in Islamic Pakistan, one can easily perceive the extent of Turkish impact on architecture and clothing, for example. Even in Hindu-dominated India, the first tourist attraction is often the Taj Mahal, which is definitely non-Hindu but also definitely Indian, culturally. One might claim that both Chinese culture and Indian culture were created by the interactions of nomadic and sedentary cultures. This is also true for Iran, Turkey, and many parts of Europe.

Most visible influences of nomads on modern Indian and Chinese societies have been dated to the middle ages. But the story started long before then. At least on the Eurasian landscape, north of the ecological zone of agriculture, between mountains and deserts, the vast steppe was probably the earliest highway of communications. Nomads, or pastoralists who lived on stock raising, had better means of transportation than did agriculturalists. The dynamics of communication and transportation, however, was derived from the need and urge to exchange goods and ideas. In studying cultural and material exchanges in premodern Eurasia, the emphasis is...