There was, indeed, a goddess, even in Erech, the centre of Semitic influence, who possessed a very strongly-marked and independent character of her own. This was Istar, of whom I shall have to speak at a future time. But it was just because Istar possessed this independent character that she could not be the wife of the god of the sky. The Semitic Baal brooked the presence of no independent goddess in the divine family; the wife of the god could not claim rights of her own any more than the wife of the man. Anu, like Bel and Ea, stood alone.
Erech had been made the capital of a temporarily united Babylonia at an early age in its Semitic history. Before the days of Sargon of Akkad, Lugal-zaggi-si--we know him only by his Sumerian name--had made himself supreme over the smaller States of the country, and even carried his arms to the distant West. In an inscription he has left us he boasts that his empire extended "from the lower sea of the Tigris and Euphrates to the upper sea," presumably the Mediterranean, as he further defines his power as stretching "from the rising to the setting of the sun." Erech became the capital of the kingdom, and it was perhaps at this time that it acquired the name which it bore ever afterwards of "the city" _par excellence_. Future ages were never allowed to forget that it had once been the premier city of Babylonia.
Lugal-zaggi-si calls himself "the priest of Anu," the god of the city which he had made the seat of his power. Anu for awhile was the god of the supreme State in Babylonia, and therefore supreme god of the whole country. The king, it is true, had come from the north, and his authority had been given him by Bel of Nippur; the old sanctuary of Nippur still claimed the first place in the religion of Northern Babylonia, and the cult of its god retained its ancient hold on the veneration of the people. But from henceforward he had to share his divine honours with another; Bel of Nippur, indeed, conferred the sovereignty, but the sovereign was priest and vicegerent of Anu. Bel and Anu were associated together at the head of the pantheon of Northern Babylonia, and the position they occupied in it became more and more unique.
So firmly established was it before the reign of Sargon of Akkad, that even his victories and the empire he founded failed to give them a colleague in the god of the new capital city. Bel and Anu remained supreme; the sun-god of Akkad or Sippar had to content himself with a subordinate rank. The theological system which put Bel and Anu at its head was already formed, and the position assigned to them by the veneration and traditions of antiquity was too firmly fixed to be shaken. Northern Babylonia worshipped a dyad in the shape of two supreme gods.