Sumer
Although short-lived, one of the first empires known to history was that of Eannatum of Lagash, who annexed practically all of Sumer, including Kish, Uruk, Ur, and Larsa, and reduced to tribute the city-state of Umma, arch-rival of Lagash. In addition, his realm extended to parts of Elam and along the Persian Gulf. He seems to have used terror as a matter of policy. Eannatum's Stele of the Vultures depicts vultures pecking at the severed heads and other body parts of his enemies. His empire collapsed shortly after his death.

Q: What is one of the first empires known in history?
Eannatum of Lagash,