It was further modified by the introduction of star-worship.

How far this went back to a belief in the "spirits" of the stars, or whether it had a Semitic origin, we do not know; but it is significant that the cuneiform character which denotes "a god" is a picture of a star, and that the Babylonians were from the first a nation of star-gazers.

In the astro-theology of a later date the gods of the pantheon were identified with the chief stars of the firmament, but the system was purely artificial, and must have been the invention of the priests.
The religion and deities of Babylonia were adopted by the Assyrians.

But in Assyria they were always somewhat of an exotic, and even the learned class invoked Assur rather than the other gods.

Assur was the personification of the old capital of the country and of the nation itself, and though the scribes found an etymology for the name in that of An-sar, the primaeval god of Sumerian cosmogony, the fact was always remembered.