An intermediate step between Anu viewed as the local deity of Erech (or some other centre), Bel as the god of Nippur, and Ea as the god of Eridu is represented by the prominence which each one of the centres associated with the three deities in question must have acquired, and which led to each one absorbing the qualities of other gods so as to give them a controlling position in an organized pantheon.
The only stone building in southern Babylonia is the town wall of Eridu (Abu Shahrein), which is built of rude lumps of a local coral rag.
The primitive seaport of the country, Eridu, the seat of the worship of Ea the culture-god, was a little south of Ur (at Abu Shahrain or Nowawis on the west side of the Euphrates).
Eridu had once been a seaport, and it was doubtless its foreign trade and intercourse with other lands which influenced the development of its culture.
Long before history begins, however, the cultures of Eridu and Nippur had coalesced.