The Soviet Empire, like many such conglomerations, slowly evolved out of centuries of aggression, anarchy and pure accident. About 500 years ago, the Muscovy state that was beginning to emerge from Mongol rule extended over just a few hundred miles on the upper reaches of the Volga. Today the U.S.S.R. represents one-sixth of the world's landmass, and its 289 million people include Armenians, Buddhists, Muslims, Tatars, Uzbeks, Yakuts -- more than a hundred different national and religious groups united mainly by their mistrust of their rulers and one another.
Before this empire was even born, the fertile steppe north of the...