The Chaldeans reigned from 625-539 BC.
Chaldean also was used by several ancient authors to denote the priests and other persons educated in the classical Babylonian literature, especially in traditions of astronomy and astrology.
Chaldea, land in southern Babylonia (modern southern Iraq) frequently mentioned in the Old Testament. Strictly speaking, the name should be applied to the land bordering the head of the Persian Gulf between the Arabian desert and the Euphrates delta.