A border created by a physical feature, such as a mountain, river, or strait

A center where cultures developed and from which ideas and traditions spread outward

A system of writing that used wedge-shaped symbols pressed into clay tablets

An underground canal first built by the ancient Persians

Large, pyramid-shaped temples made of mud-brick, created by the Sumerians

A ban on trade

A tributary that leads to a larger river

A wetland typically covered with grasses

Wide, grassy plains of Central Asia

Any grain like barley, oats, or wheat that is grown for food

Islamic guerilla warfare fighters in Afghanistan that were opposed to the invasion of the Soviet Union

From Arabic for "seeker" or "student"; name of a fundamentalist Sunni Muslim group, active in Afghanistan, which controlled the Afghan government from 1996 to 2001

A territory that belongs to a particular political unit but is separated from it and surrounded by another political unit

A territory surrounded by another political unit that it does not belong to

Contamination by residue from the generation of nuclear energy or the testing of nuclear weapons

Ethnic group that lives in parts of Iraq and Turkey. They often suffer persecution in both countries. They are the largest ethnic group in the world that does not have its own country

The people who dominated southern Mesopotamia through the end of the third millennium B.C.E. They were responsible for the creation of many fundamental elements of Mesopotamian culture-such as irrigation technology, cuneiform, and religious conceptions

Sea between Europe and Asia that is north of Turkey. Its connects with the Aegean Sea by way of the Bosporus and Dardanelles (Turkish Straits) and the Sea of Marmara

A large saltwater lake between Iran and Russia fed by the Volga River; world's largest inland body of water