(Chal·deʹa), Chaldean (Chal·deʹan).

Originally the land and people occupying the southern portion of the Babylonian alluvial plain, the rich delta area of the Tigris and Euphrates rivers. At one time these rivers may have emptied into the Persian Gulf separately, the cities of Eridu and Ur being seaports. But over the years the river silts may have gradually filled in the bay, pushing the coastline to the SE and allowing the Tigris and Euphrates to join together before emptying into the sea. In early times the region’s most important city was Ur, the hometown of Abraham, from which he and his family departed at God’s command before 1943 B.C.E. (Ge 11:28, 31; 15:7; Ne 9:7; Ac 7:2-4) About 300 years later Satan the Devil caused Chaldean raiders to inflict heavy losses on faithful Job.​—Job 1:17.

As the influence of the Chaldeans spread northward, the whole territory of Babylonia became known as “the land of the Chaldeans.” Isaiah in his prophecies anticipated this Chaldean rise to power and their subsequent fall. (Isa 13:19; 23:13; 47:1, 5; 48:14, 20) Particularly was this domination manifest during the seventh and sixth centuries B.C.E. when Nabopolassar, a native of Chaldea, and his successors, Nebuchadnezzar II, Evil-merodach (Awil-Marduk), Neriglissar, Labashi-Marduk, Nabonidus, and Belshazzar, ruled the Third World Power, Babylon. (2Ki 24:1, 2; 2Ch 36:17; Ezr 5:12; Jer 21:4, 9; 25:12; 32:4; 43:3; 50:1; Eze 1:3; Hab 1:6) That dynasty came to its end when “Belshazzar the Chaldean king was killed.” (Da 5:30) Darius the Mede was “made king over the kingdom of the Chaldeans.”​—Da 9:1; see BABYLON No. 2.

From early times the Chaldeans were noted for their knowledge of mathematics and astronomy. In the days of Daniel a special cult of prognosticators who considered themselves skilled in the so-called science of divination were called Chaldeans.​—Da 2:2, 5, 10; 4:7; 5:7, 11.