Ancient Mesopotamia is the country now called Iraq. Its northern part, down to an imaginary line running east-west slightly north of modern Baghdad, constituted ancient Assyria, with the cities of Ashur (modern Qalʾat Shergat), which was the old capital; Calah (Nimrud); and Nineveh (Kouyundjik), which took its place later, at the time of the Assyrian empire in the first millennium BCE. The country consists of rolling plains resting on a bed of rocks. Rainfall over most of the area is sufficient to sustain a cereal crop. The main river is the Tigris, which traverses the country from northwest to southeast. The language spoken in historical times was Assyrian, a dialect of Akkadian, a Semitic language related to Hebrew and Arabic.

The southern part of Mesopotamia, south of the imaginary line mentioned, was ancient Babylonia, with Babylon (Babil) as its capital. The...