She is indeed explicitly called the consort of Nin-girsu; and this relation is implied also, in the interesting phrase used by Gudea, who presents gifts to Bau in the name of Nin-girsu, and calls them 'marriage gifts'.[34] It is interesting to find, at this early period, the evidence for the custom that still prevails in the Orient, which makes the gifts of the bridegroom to his chosen one, an indispensable formality.[35] These gifts were offered on the New Year's Day, known as Zag-muk, and the importance of the worship of Bau is evidenced by the designation of this day, as the festival of Bau.
The offerings, themselves, consist of lambs, sheep, birds, fish, cream, besides dates and various other fruits.

When Uru-azagga becomes a part of Lagash, Bau's dignity is heightened to that of 'mother of Lagash.' As the consort of Ningirsu, she is identified with the goddess Gula, the name more commonly applied to the 'princely mistress' of Nin-ib, whose worship continues down to the days of the neo-Babylonian monarchy.
It is quite certain, however, that Bau is originally an independent goddess, and that the association of Uru-azagga and Girsu[36] lead to her identification with Gula.

Regarding her original nature, a certain index is her character as "daughter of Anu." Anu being the god of heaven, Bau must be sought in the upper realm of personified forces, rather than elsewhere; but exactly which one she is, it is difficult to say.

Hommel, indeed,[37] is of opinion that she is the personified watery depth, the primitive chaos which has only the heavens above it; but in giving this explanation, he is influenced by the desire to connect the name of Bau with the famous term for chaos in Genesis, _Tohu-wa-bohu_.

There is, however, no proof whatsoever that Bau and Bohu have anything to do with one another.