The oppressed people of Assyia joined up with the lesser tribes of Medes and Chaldeans

Together, they defeated the Assyrians

The Babylonians split the empire into two:

Medes: Highlands to the north of the Assyrian Empire
Chaldeans: Mesopotamian Proper

Chaldeans were mostly Babylonians

The capital city was Babylon were they get their name

They advanced the study of mathematics, astronomy, and astrology