Chaldea

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 כשדים, Kaśdîm/Kaśdîn, 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 Chaldeans were a Semitic people of Arabian origin who settled in southern Mesopotamia in the early part of the first millennium BC. Their language is assumed to be related to Aramaic, although they settled much further to the south than the Aramaeans, who settled in upper Mesopotamia and Syria. The Chaldeans soon made their influence felt in Babylonian politics, and several 9th and 8th century BC Babylonian kings were of Chaldean origins. During the period of Assyrian domination of Babylonia, the Chaldeans formed some of the strongest resistance to Assyrian rule. King Marduk-apla-iddina II, who resisted the Assyrians in the times of Sargon II and the early years of Sennacherib, and King Mushezib-Marduk, who was king just before Sennacherib's sack of Bayblon in 689 BC, were both Chaldeans. When Babylonia finally reestablished its independence, it was under a probably Chaldean dynasty, that of Nabopolassar. After the conquest of Babylonia by the Persians, the Chaldeans disappear as a separate people.

Roman and later authors used the name Chaldeans in particular for astrologers and mathematicians from Babylonia.

In modern times, a million or so Mesopotamian Roman Catholics call themselves Chaldeans.