Designation used from the 8th century B.C. for the land (kur kal-du) in the southeastern territory of Mesopotamia, including the borders of Elam in the Zagros mountains and the "Sealand" around the Persian Gulf. It was named after the "Chaldean" people (lu kal-du or kal-da-ay-ya), a semi-nomadic west semitic tribe which had most likely moved into the region some time between the 10th and 9th centuries B.C. They assumed a role of champions of Babylonian independence (naturally, under Chaldean rule) against the Neo-Assyrian empire, and provided the famous rulers Nabopolassar and Nebuchadnezzar of the Neo-Babylonian empire. Chaldea and Chaldeans in the Bible and classical sources generally refer to the land or people, respectively, of Babylonia as a whole, or to their function as priests and astrologers, specifically.
Chaldeans are first attested in the time of the Assyrian king Assurnassirpal II, around 878. When they first entered Mesopotamia, but it must have been some time in two centuries before, during the 'dark age' of Mesopotamian history. It has been suggested that the Chaldaeans were an Aramaean sub-group, though this is far from certain. We know of three major tribes (the Bit-Amukani, Bit-Dakkuri, and Bit-Yakin) already active in the 9th century. Each tribe seems to have been scattered throughout the fringe- and marshlands around the southern Tigris and Euphrates, living from subsistence agriculture, pastoralism, and a yet ill-defined role on the trade-routes to the Persian Gulf.
Since the reign of Shamshi-Adad V (823-811) in Assur, Mesopotamia had been under more or less firm Assyrian control. Revolutions attempting to place a native king on the throne in Babylon usually ended under the violent hand of the impressive Assyrian military machine. At the ascension of Sargon II, however, in 720 BC, the Chaldean Marduk-Apla-Iddina II (the Merodach-Baladan II of the Bible) of the tribe Bit-Yakin managed to oust the Assyrian governor in Babylon and declare himself king. Despite numerous attempts to retake the city, Sargon would have to wait 12 years before he could drive the usurper back into the southern marshes. Since Sargon was unable to pursue Marduk-Apla-Iddina into the swamps, the Chaldean leader escaped, only to attempt to take the throne twice more (though unsuccessfully).
The important point here is that the Chaldean tribes, by their very structure and lifestyle, formed the ideal guerilla army against Assyrian domination. While it was easy for the Assyrian army to besiege and burn the cities (and they did, including Uruk, Ur, and Babylon), it was impossible for them to crush a decentralised enemy in the desert. Naturally, our Assyrian sources describe the Chaldeans as a seditious, chaotic element in the political scene.
Let's skip a few more years of history (note to self, node an essay on the Assyrian empire sometime soon), and turn to the collapse of Assyria. Assurbanipal (668-631?) was finally able to crush his country's age-old rival, Elam in Iran in 647, after the Iranian state had supported a 4-year rebellion in Babylon (which was also pillaged and burned). Unfortunately, this also removed a valuable buffer zone between Mesopotamia and the savage, marauding Medes of the Iranian interior. When Assurbanipal's successor, Assur-etil-ilani, took the throne (631? 627? note to self, never node the chronology of Mesopotamia between 631-612), the Chaldean Nabopolassar was already well on the way towards independence on the Babylonian throne. By 612, the city of Assur had been looted, Nineveh razed to the ground, by a combined army of Medes and Chaldeans.
Neo-Babylonian history under this Chaldean dynasty also belongs elsewhere. Let's just say that until the Persians arrived on the scene, Babylon formed the last great Mesopotamian empire, dominating the entire Near East, including (temporarily) parts of Egypt. Babylonian culture, including astronomy, astrology, mathematics, and literature, reached a peak it had not seen since Hammurabi. Business documents and letters attest a thriving economy long since recovered from the ashes of Assyrian conquest. Most importantly, perhaps, this is also the Chaldean Babylon which the first Greek travellers experienced, and which spread its culture and knowledge throughout the Mediterranean world.
This perhaps goes a long way towards explaining the Chaldean reputation in later times. The Bible, quite understandably, equates the Babylonians with the Chaldeans. Thus, while in Job 1:17 we are reminded of past Chaldean raids, the book of Daniel speaks of the prophet learning "Chaldean writing and language" (Dan 1:4). These Chaldeans are even quoted in Aramaic, the vulgar tongue of the late Babylonian age. From here, it is a short step to the Chaldean astrologers and magicians of the classical age. Their role as such is still unclear in Herodotus, but tradition holds that the Babylonian priest and astronomer Berossus titled the history of his own land the "Historia Chaldaika". By the time of the early Roman Empire, Strabo could already confidently write about the Chaldeans as just another tribe of astrologers involved in petty arguments on the stars, without a thought to their role in the course of history just six centuries before.
Consarnit, I'd forget my head if it weren't attached. Citations:
- Kuhrt, Amelie. The Ancient Near East. (Routledge 1997). Beautiful introduction to ancient Near Eastern history, readable, with an extensive bibliography. In two volumes, and not too expensive.
- Frame, Grant. Babylonia 689-627 B.C. (Leiden 1992). I don't know if this is still available, but his is an excellent study of the period. For a (revised) dissertation, a pretty fluid read. He is also one of the best authorities for Near Eastern history in general.
- Brinkman, J.A. A Political History of Post-Kassite Babylonia, 1158-722. (Rome 1968). Available only through your local library, if you're lucky, but gives the best discussion of the origins of the Chaldeans.