Uruk, now known as Warka, was occupied for at least 5,000 years, from early in the Ubaid period until the third century AD. By the end of the fourth millennium BC the site had become the largest urban centre in Mesopotamia, if not the world. There may have been two original settlements, later known as Kullaba and Eanna. These two areas of the city had monumental mud brick platforms and temple buildings; those in Eanna were associated with the goddess Inana (Ishtar).
The earliest evidence for writing in Mesopotamia was discovered in Eanna, though it is difficult to date precisely: the writing is on clay tablets that had been used as packing for foundations of later buildings. The city was surrounded by a wall that, according to later accounts, was built by Gilgamesh, a legendary king of the city. After the third millennium BC Uruk declined politically but it remained an important religious centre and its shrines were embellished by many of the later rulers of Mesopotamia. From 1912 onwards, major excavations have been undertaken by the Deutsche Orient-Gesellschaft.