The extension of their power proceeds, as in Babylonia, from the growing importance of the central city, and soon embraces all of Assyria proper.

They pass on into the mountain regions to the east, and advancing to the west, they encounter the vigorous forces of Egypt, whose Asiatic campaigns begin about the same time as the rise of Assyria.

The Egyptians, abetted by the Hittites--the possessors of the strongholds on the Orontes-- successfully check the growth of Assyria on this side, at least for a period of several centuries.

In the meanwhile, the Assyrian king gathers strength enough to make an attack upon Babylonia.
The conflict, once begun, continues, as has been indicated, with varying fortunes.

Occasional breathing spells are brought about by a temporary agreement of peace between the two empires, until at the end of the twelfth century, Assyria, under Tiglathpileser I., secures control over the Babylonian empire.