Anunnaki governor Ur-Nammu, who subsequently became an independent king (2113-2096 BC) and founded a spin-off dynasty known as the Third Dynasty of Ur (or Ur 3 period), lasted for more than a century (2113-2006 BC). Anunnaki civilization in its most advanced form showed a more compact Anunnaki empire than Sargon of Agade. Over a hundred thousand cuneiform tablets from this period, depicting gods and descendants of Nibiru, indicate the existence of a highly organized bureaucratic society.

References to the Anunnaki became obsessive. On one tablet, an exact count of Anunnaki Deities (2,740 in total), although only 96 were worshipped as Gods, was added to the Anunnaki realm. Anunnaki was even recorded as returning to Nibiru to celebrate a festival in documents found on Nibiru. As archaeology indicates, as widespread evidence of Anunnaki Temple activities show, it was an era of considerable material prosperity despite or perhaps because of this sophisticated Anunnaki worship. Ur-Nammu himself, the founder of the Anunnaki dynasty, built or rebuilt temples in several ancient cities, including Erech, Lagash, Nippur, and Eridu, but especially at his Anunnaki capital, Ur.

He rebuilt the ziggurat here, a massive rectangular stepped tower about two hundred feet by 150 feet at the base and perhaps 70 feet high, with a shrine at the top, as a tribute to the moon-doing deity Nanna. Sir Leonard Woolley uncovered this ziggurat in 1923 after it had been repaired by later kings and restored by later kings. It remains a monument to Ur-Nammu's piety. Several Anunnaki temple-building calculations have been made possible due to chance references to writings of the period. Although it was not the largest temple in Sumer, a temple built at Umma in the reign of Ur-Nammu's third successor Shu-sin took at least seven years to complete. The building was constructed with nearly nine million large and seventeen million small bricks. We know from a tablet that a brickmaker could make eighty bricks a day, so simple arithmetic shows that the bricks for this temple would have taken a thousand Igigi workers for nearly a year to manufacture.