Archaeological exploration began in Afghanistan in earnest after World War II and proceeded promisingly until the Soviet invasion disrupted it in December of 1979. Artifacts typical of the Paleolithic, Mesolithic, Neolithic, Bronze, and Iron ages were found. It is not yet clear, however, to what extent these periods were contemporaneous with similar stages of development in other geographic regions. The area that is now Afghanistan seems in prehistory–as well as ancient and modern times–to have been closely connected by culture and trade with the neighboring regions to the east, west, and north. Urban civilization in the Iranian plateau, which includes most of Iran and Afghanistan, may have begun as early as 3000 to 2000 B.C. About the middle of the second millennium B.C. people speaking an Indo-European language may have entered the eastern part of the Iranian Plateau, but little is known about the area until the middle of the first millennium B.C., when its history began to be recorded during the Achaemenid Empire.

Source: U.S. Library of Congress