In an unexpected benefit of the cold war's end, Russian and American archaeologists say they have discovered an ancient civilization that thrived in Central Asia more than 4,000 years ago, before being lost in the sweep of history. The people of that area, the archaeologists say, built oasis settlements with imposing mud-brick buildings and fortifications. They herded sheep and goats and grew wheat and barley in irrigated fields. They had bronze axes, fine ceramics, alabaster and bone carvings and jewelry of gold and semiprecious stones. They left luxury goods in the graves of an elite class. The accomplishments of those...