“The Chaldean magician was a master of the 'Incantation of the Spirits,' believing that every force in nature was governed by a divine essence that could be summoned or bound through the precise vibration of sacred words.” ― Lenormant, F. (1877). Chaldean Magic: Its Origin and Development
The Chaldeans were a specific West Semitic tribal group that migrated into southern Mesopotamia around the 10th or 9th century BC, whereas the Babylonians were an East Semitic Akkadian-speaking people who had inhabited the region for millennia prior.
Initially distinct, the Chaldeans rose to political power in the late 7th century BC by establishing the Neo-Babylonian Empire. As Chaldean kings like Nebuchadnezzar II ruled Babylon, the term "Chaldean" gradually became interchangeable with "Babylonian" to refer to the empire's inhabitants, its rulers, and its highly educated class of astrologers and wise men. Consequently, while they originated as different ethnic groups, the Chaldeans effectively merged into Babylonian culture, leading to their later identification as one and the same in historical and religious records.