Unlike the Akkadian speaking Assyrians and Babylonians, the Chaldeans were certainly not a native Mesopotamian people, but were migrants to the region. They seem to have appeared there c. 1000 BC, not long after other new Semitic peoples, the Arameans and the Sutu appeared in Babylonia, c. 1100 BC. This was a period of weakness in Babylonia, and its ineffectual native kings were unable to prevent new waves of foreign peoples invading and settling in the land.
Sunday school this morning read through Genesis 20, the "table of nations" descended from the sons of Noah. I noticed something that I'd never noticed before. The cities that would later be prominent as Assyria and Babylon, are Hamitic, not Semitic. Aram, on the other hand, is Semitic, and northward of Caanan.