Mesopotamia (Sumer/Babylon)

Mesopotamian civilisations — Sumer, Akkad, Babylon, and Assyria — produced humanity's first writing system (cuneiform), first legal code (Hammurabi), first cities, first organised religion, first mathematics using base-60 (still used for time and angles), and the first literature (the Epic of Gilgamesh, the world's oldest written story). Everything we call "civilisation" has its roots in the Tigris-Euphrates valley.