Chaldea was a nation in the southern portion of Babylonia, Lower Mesopotamia, lying chiefly on the right bank of the Euphrates, but commonly used to refer to the whole of the Mesopotamian plain. The Hebrew name is כשדיםKaśdîm, which is usually rendered "Chaldeans" (Jeremiah 50:10; 51:24,35).
Chaldea was a vast plain formed by the deposits of the Euphrates and the Tigris, extending to about 400 miles along the course of these rivers, and about 100 miles in average width.
The Chaldees were a tribe (that is believed to have migrated from Arabia) that lived on the shores of the Persian Gulf, and become a part of the Babylonian around the time of Hezekiah.
The Biblical ancestor of the Hebrew people, Abraham, was born at "Ur of the Chaldees," since the Chaldean people (Chaldees) ruled Babylonia during the Babylonian captivity (when the Hebrews wrote the Torah). Ur was one of the oldest and most famous of the Babylonian cities. Its site is now called Mugheir on the western bank of the Euphrates, in Southern Babylonia. About a century before the birth of Abraham it was ruled by a powerful dynasty of kings. Their conquests extended to Elam on the one side, and to the Lebanon on the other. They were followed by a dynasty of princes whose capital was Babylon, and who seem to have been of South Arabian origin. The founder of the dynasty was Sumu-abi ("Shem is my father"). But soon afterwards Babylonia fell under Elamite dominion. The kings of Babylon were compelled to acknowledge the supremacy of Elam, and a rival kingdom to that of Babylon, and governed by Elamites, sprang up at Larsa, not far from Ur, but on the opposite bank of the river. In the time of Abraham the king of Larsa was Eri-Aku, the son of an Elamite prince, and Eri-Aku, as has long been recognized, is the Biblical "Arioch king of Ellasar" (Genesis 14:1). The contemporaneous king of Babylon in the north, in the country termed Shinar in Scripture, was Khammurabi. (See Amraphel)
While the Bible claims that Abraham was from Ur of the Chaldees, a look at the time period in the book of Genesis makes it clear that if Abraham were from Ur, it would not have been yet known as the Chaldees. Since the discovery of Ur, very few scholars would argue that Abraham (if he existed at all) was from Ur, and therefore probably a Sumerian.
