Sumer

Sumer (rather than Sumeria) was a civilisation that existed in southern Mesopotamia (modern Iraq), along the valleys of the Tigris and Euphrates rivers, from around 4500 BC to around 1900 BC. It's the earliest known civilisation in that region, and one of the earliest in the world – along with Ancient Egypt and the Indus Valley. Uruk, Ur and Eridu were three of its principal city–states (flourishing at different times).

Ur is believed by many to be the city mentioned in the Book of Genesis as Ur Kasdim, the birthplace of Abraham – who is traditionally believed to have lived some time in the second millennium BC.

The Sumerians were characterised by their inventiveness, and developed what was probably the world's first writing system. They wrote on tablets of clay, later evolving the script that's known today as cuneiform, or 'wedge–shaped.'

Gilgamesh – the protagonist of what is often regarded as the earliest surviving great work of literature – was a ruler of Uruk, who lived some time between around 2800 BC and around 2500 BC.