Sumerian religion was city religion. Each city belonged to its god, whose temple was literally the god's household: Enlil, lord of the air and executive of the divine assembly, ruled from the Ekur at Nippur, the land's religious capital; Nanna the moon lit Ur; Enki, cunning lord of the sweet waters beneath the earth, kept the divine ordinances at Eridu, which Sumerian tradition counted the oldest city in the world; and Inanna, goddess of love and war, the morning and evening star, shared Uruk with the sky father An, the remote head of the pantheon. The temple stood on a raised platform that grew into the ziggurat, and its staff fed, clothed and housed the god's statue while managing estates, herds and workshops on the god's behalf.
The gods ran the cosmos as an assembly under An and Enlil, apportioning destinies; kingship, as the Sumerian King List puts it, descended from heaven and moved from city to city. Humanity existed to relieve the gods of labor, a bargain told in the myths with unsentimental clarity, and divination, omens and lament kept the relationship in repair.
The literature recovered from the scribal schools, translated in Jeremy Black and colleagues' Literature of Ancient Sumer and the online corpus that grew from it, is the oldest in the world: Inanna's descent to the underworld, the disputations of plough and hoe, temple hymns attributed to Enheduanna, priestess and first named author in history, and the poems of Gilgamesh of Uruk that Babylon later wove into its great epic.