For the writers of Greece and Rome the Babylonians are Chaldaeans.

It is probable that Nebuchadrezzar was of Kalda origin; if so, this would have been a further reason for the extension of the tribal name to the whole country.
The settlement of the Kalda in the marshes was of comparatively late date.

Indeed, in the early age of Babylonian history these marshes did not as yet exist; it was not until Eridu had ceased to be a seaport that they were reclaimed from the sea.

The Kalda were the advance-guard of the Nabatheans and other Aramaic tribes of northern Arabia, who migrated into Babylonia and pitched their tents on the banks of the Euphrates, first of all as herdsmen, afterwards as traders.

After the fall of the Babylonian monarchy their numbers and importance increased, and the Aramaic they spoke--the so-called "Chaldee"-- came more and more to supersede the language of Babylonia.
When first we get a glimpse of Babylonian history, the country is divided into a number of small principalities.