The Old Assyrian Empire (Sumero-Akkadian cuneiform: 𒆳𒀭𒊹𒆠 KUR AN-ŠAR2KI, Assyrian cuneiform: mat aš-šur KI, "Country of the city of god Aššur"; also phonetically mat da-šur)[a] is the second of four periods into which the history of Assyria is divided, the other three being the Early Assyrian Period (2600–2025 BC), the Middle Assyrian Empire (1392–934 BC), and the Neo-Assyrian Empire (911–609 BC). Assyria was a major Mesopotamian East Semitic-speaking kingdom and empire of the ancient Near East. Centered on the Tigris–Euphrates river system in Upper Mesopotamia, the Assyrian people came to rule powerful empires at several times. Making up a substantial part of the "cradle of civilization", which included Sumer, the Akkadian Empire, and Babylonia, Assyria was at the height of technological, scientific and cultural achievements at its peak.
At its peak, the Assyrian empire ruled over what the ancient Mesopotamian religion referred to as the "four corners of the world": as far north as the Caucasus Mountains within the lands of what is today called Armenia and Azerbaijan, as far east as the Zagros Mountains within the territory of present-day Iran, as far south as the Arabian Desert of today's Saudi Arabia, as far west as the island of Cyprus in the Mediterranean Sea, and even further to the west in Egypt and eastern Libya.
Assyria is named for its original capital, the ancient city of Assur, which dates to c. 2600 BC, originally one of a number of Akkadian city states in Mesopotamia. Assyria was also sometimes known as Subartu and Azuhinum prior to the rise of the city-state of Assur, and during the Sasanian Empire as Asōristān.