Ancient Greeks had a word for the people who lived on the wild, arid Eurasian steppes stretching from the Black Sea to the border of China. They were nomads, which meant “roaming about for pasture.” They were wanderers and, not infrequently, fierce mounted warriors. Essentially, they were “the other” to the agricultural and increasingly urban civilizations that emerged in the first millennium B.C.

As the nomads left no writing, no one knows what they called themselves. To their literate neighbors, they were the ubiquitous and mysterious Scythians or the Saka, perhaps one and the same people. In any case, these nomads were looked down on — the other often is — as an intermediate or an arrested stage in cultural evolution. They had taken a step beyond hunter-gatherers but were well short of settling down to planting and reaping, or the more socially and economically complex life in town.

But archaeologists in recent years have moved beyond this mind-set by breaking through some of the vast silences of the Central Asian past.

These excavations dispel notions that nomadic societies were less developed than many sedentary ones. Grave goods from as early as the eighth century B.C. show that these people were prospering through a mobile pastoral strategy, maintaining networks of cultural exchange (not always peacefully) with powerful foreign neighbors like the Persians and later the Chinese....