Chaldea, properly the name of the S. W. part of ancient Babylonia, bordering on the N. E. confines of Arabia. So it is mentioned by Ptolemy the geographer. Strabo also speaks of a Chaldean tribe living in that region. This district comprised the most fertile plains of Babylonia, made wonderfully productive by the numberless canals constructed by the rulers of that empire for defence, commerce, and irrigation. But commonly the name is applied to Babylonia in general, designating the whole of the province, sometimes even the empire of that name. The Hebrew term, probably for all these meanings, is Chasdim, or land of the Chasdim (Chaldees). The latter first appear in the Scriptures as the owners of the region which was the abode of the ancestors of Abraham, then as a conquering tribe and nation, and besides as a caste of priests or astrologists. The Ur Chasdim (Ur of the Chaldees) of Abraham was considered by many modern critics to have been a place in Mesopotamia, and identical with the castle of the same name, mentioned by Ammianus as situated between Nisi-bis and the Tigris. This, as well as the circumstance that Chaldeans are mentioned by Herodotus as soldiers in the Assyrian army of Xerxes, and by Xenophon, in the history of the retreat of the ten thousand, as a free and warlike people in the Carduchian mountains, made it appear probable that the original home of this nation was among, or at least near, the mountains of Armenia, whence they made their incursions, it was supposed at different periods, into the neighboring southern countries, sub-duing Babylon, and afterward Syria. Gesenius supposed their name to have been originally Card, which was changed into Chasd and Chald, and preserved in that of the modern Kurds, inhabiting the region of the ancient Carduchi. Their Semitic descent seemed to be proved by the language called after them; so Josephus represents them as descendants of Arphaxad, son of Shem, the latter part of that compound name supporting his opinion.

But there remained considerable difficulties in critically establishing the early history of this nation. Nimrod, the mighty hunter, who is mentioned in the book of Genesis as the founder of the empire of Babylonia, which is afterward styled the land of the Chaldees, was a Hamite, and seems to have extended his conquest northward, at least according to an almost generally adopted explanation of the passage which speaks of him. The Greeks name Belus as the founder of the same empire. Nothing is said in the Bible about the nation to which belonged Amraphel, the king of Shinar, that is, Babylonia, who fought a battle in Palestine in the days of Abraham; and a chasm of about 13 centuries separates the first mention of the Chaldeans, in connection with the Ur of the ancestors of the patriarch, from their next reappearance in the Scriptural history, in the time of Isaiah (except their being mentioned in the book of Job as capturing the camels of the patriarch of Uz); while Babylonia, which appears first at the same time in relation with the history of the Hebrews, is known from the testimony of the classical writers to have existed during this whole period as a highly developed state, by turns conquering and conquered, a product of its advanced industry being also mentioned in the history of Joshua. A natural consequence of these dates would therefore have been the conclusion that Babylonia, having been founded by Nimrod or Belus, be these names identical or not, had reached a high degree of culture, might, and glory before it was conquered by the warlike tribe who made Babylon the centre of greater conquests, power, and civilization, "the beauty of the Chaldees' excellency," as it is called in Scripture, the Chaldaicarum gentium caput, as Pliny calls it.

Thus the history of this nation, as masters of Babylonia, would be dated either from the year 747 B. C, the first of the so-called Chaldean era of Nabonassar in the astronomical canon of Ptolemy, who makes him the first of a series of 19 princes of this nation who ruled the great city after the fall of the first Assyrian empire; or from the reign of Nabo-polassar, who in alliance with Cyaxares, king of the Medes, broke the yoke and conquered the capital of the Assyrian state, thus founding the independence of Babylonia, and its predominance in western Asia, which his son Nebuchadnezzar so vastly extended. But this conclusion is weakened by the circumstance that Babylon is known to have been already in the most remote periods of history the seat of a system of religious worship and science, which in antiquity was generally attributed to the genius and made the glory of the Chaldeans, whose name both in Biblical and classical antiquity designates not only the nation, but also the peculiar priest caste devoted to the sacred science of astrology; it being also mentioned that Callisthenes, who accompanied Alexander on his expedition to Persia, sent Aristotle a collection of astronomical observations made by the Chaldeans in the temple of Belus, their observatory, during a period of no less than 1,1)03 years.

It is moreover shaken by the contents of the fragments of the Babylonian historian Berosus, which though full of extravagant legends, at least prove a very ancient belief that the Chaldeans were the earliest or among the earliest organizers of Babylonian society. Berosus speaks of an antediluvian dynasty of Chaldean kings, during the early time of which Oannes, an extraordinary being, half man, half fish, speaking with a human voice, came out of the waves of the Erythraan sea to teach the inhabitants of the shore religion and laws, science, art, and industry, retiring every evening into the sea and reappearing every morning. He and his successors became the civilizers of the people of Babylonia. Some critics have seen in this myth of Oannes a confirmation of a relation of Diodorus, according to which a colony from Egypt headed by Belus, the son of Poseidon and Libya, carried the science of their land over the sea to the inhabitants of the Babylonian plains, which served to vindicate the claims of the Egyptians for the priority of their astronomical knowledge over that of their great Asiatic rivals; while others regarded the Chaldeans as the fathers of astronomy, and their country as the focus of this science, whence it spread to India, Egypt, and the West. The third dynasty of the postdiluvian kings of Berosus is also Chaldean. The most plausible way of reconciling the discrepancies in the testimony of the ancients seemed to the critics of the school of Gesenius, whose dissertation on the Chaldeans in the Encyldoyiidic of Ersch and Gruber was long regarded as the best solution, to be to sum up the history of the Chaldeans as follows: Their first home is either in the mountains of Armenia, or somewhat further N. in those of the Caucasus, or further S. in those of Kurdistan; their Scriptural ancestor being either Arphaxad, son of Shem, or Chesed, son of Nahor, likewise a Shemite. They spread over Mesopotamia and made incursions into Babylonia. A colony of them, soon after the foundation of Babylon, establishes the influence of their priest caste in that state.

Like the Brahmans of India, they rule the public worship, and through it the laws and manners of the Babylonians. They develop art, industry, and commerce, but above all the science of astronomy and astrology. They occupy the highest rank in the state, and its governors or viceroys in the period of subjection to Assyria are chosen from their body, of which is also Nabonassar, who heads the series of Ptolemy's 19 Chaldean princes, probably vassals of the Assyrian empire. One of these princes is Merodach-bala-dan (mentioned also under this name by Berosus, and under that of Mardokempad by Ptolemy), who in the time of Sennacherib sends ambassadors to Hezekiah, king of Judah, probably with the object of forming an alliance against the common oppressor. His successor, Belibus, is carried away as captive by Sennacherib, who makes his own son Esarhaddon (the Asordon of Berosus) viceroy of Babylonia. In the mean time the stock of the Chaldean nation remains in their native mountains, warlike, fierce, and predatory.

They appear as plundering invaders in the book of Job, and at a later period as Persian soldiers in the history of Herodotus, and as a warlike mountain tribe in Xenophon's Anabasis. Strengthened by new immigrations of this warlike people, Na-bopolassar, the Chaldean viceroy of Babylonia, shakes oft' the yoke of New Assyria, destroys Nineveh with Cyaxares, and thus becomes the founder of the Chaldean empire, now properly so called. Its limits, power, and glory are vastly extended by his son Nebuchadnezzar, who leads his fierce armies and the hosts of his vassals as far as Egypt, or, according to the legend, as for as the pillars of Hercules, peoples his provinces with nations carried into captivity, and adorns his enlarged capital with the treasures of destroyed cities and sanctuaries, with palaces, temples, and magnificent gardens. The Chaldeans are now the nation of Babylonia, though their priests appear also under this name as a caste, or at least as a numerous college, similar to that of the magi of the Medes, devoted to the science of the stars and to the religious practices connected with it.

Through Nebuchadnezzar's conquests Babylon is made "the mistress of kingdoms," who says in her heart, "I am, and there is nothing else beside me." But half a century later "the golden city," enervated by luxury and extravagance, becomes an easy prey to the warlike Medes, " who do not regard silver, nor delight in gold." The "bitter and hasty" nation of the Chaldeans disappears as such, and its name is preserved for some time only in scattered tribes, and its glory in the science of its priests. The determination of the lunar periods, that of the equinoctial and solstitial points, a more precise definition of the solar year, the division of the ecliptic into 12 equal parts, that of the day into hours, the signs, names, and figures of the zodiac, the invention of the dial, are some of the improvements in astronomy attributed to the knowledge of the Chaldeans. With the decline of Babylon their science sinks, and the Chaldeans are afterward known among Greeks and Romans only as astrologers, magicians, and soothsayers, and as such despised, and finally persecuted by some of the emperors. - This scheme of Chaldean history, as far as it relates to the northern origin of the people, is invalidated, though not overthrown, by the results of the archaeological researches based on the recent discoveries among the ruins of Babylonia and Assyria. (See Cuneiform Inscriptions.) The main points of these results may be briefly summed up as follows: About the year 2234 B. C. the Cushite inhabitants of southern Babylonia, probably a people identical with the Kaldi mentioned in Assyrian inscriptions of much later date, and of a cognate race with the primitive settlers both of Arabia and of Ethiopia, are supposed to have first risen into importance.

Delivered from the yoke of the Medes, whose reign is mentioned by Berosus as that of the first postdiluvian dynasty, they established a native dynasty, founding an empire, whose earliest capitals (the southern or lower tetrapolis) were Hur or Huruk, supposed to be the Scriptural Ur, now Mugheir; Erech, now Warka, or Urka, the great necropolis of Babylonia; Larsa, the Scriptural Ellasar, now Senkereh; and Nipur (perhaps identical with the Scriptural Calneh), the city of Belus, now Niffer. Another tetrapolis, in the northwest, is supposed to have been formed by Babel, Borsippa, Cusha, and Sippara. The city which the oldest inscriptions seem to mark as the Cushite capital is Hur, the southernmost of all, a little below 31° N. lat., near the W. bank of the Euphrates. Its site is presumed to have been originally on the shore of the Persian gulf, which subsequently receded. These Cush-ites introduced the worship of the heavenly bodies in place of the elemental religion of the magian Medes. In connection with this planetary adoration, whereof the earliest traces appear in the temples of the moon at Mugheir, of the sun at Senkereh, and of Bel and Beltis (or Jupiter and Venus) at Niffer and Warka, the movements of the stars were observed and registered, astronomical tables formed, and a chronological system founded thereupon, such as continued uninterrupted to the days of Callisthenes and Berosus. To this primitive Cushite dynasty, which is probably represented in the Bible by Nimrod, the son of Cush, the two earliest of the monumental kings, Urukh or Urkham and his son Ilgi, may be assigned.

The former, whose seal cylinder is preserved, is described on the monuments as king of Hurand Kingi-Akkad (the Scriptural Accad). The next names on the monuments, in point of antiquity, are Sintishil-Hak and his son Kudur-mabuk or Kudur-mapula. This latter king is designated as the "ravager of the west," and may easily be identified with the Scriptural Chedorlaomer, king of Elam, or Susiana, a country inhabited by a Cushite race; and it is presumed that at this period the Elymreans stood at the head of a confederacy of Cush-ites, Semites, Aryans, and Turanians, of whom Chedorlaomer, Amraphel, king of Shinar or Babylonia proper, Arioch, king of Ellasar, and Tidal, king of various Turanian "nations," were the respective national chiefs. This combination of races probably gave rise to the name Kiprath-arbat (four tongues), given to the Babylonian people in the inscriptions. Under the Elymaean dynasty, which corresponds to the second postdiluvian Chaldean of Berosus (1976 -1518 B. C), the seat of power was removed northward to the upper tetrapolis, while on the Tigris were laid the foundations of the Semitic realm of Assyria. Several names of the Elymaean dynasty have been recovered from the monuments, among them that of Khammarubi, the builder of temples and constructor of the old royal canal, who gathered the people of "Sumir and Akkad," supposed to have been the chief races of Babylonia, into cities.

The following dynasty is designated in Berosus as the Arabian (1518-1273 B. C). It indicates the overthrow of the Cushite (" Chaldean") ascendancy by a new Semitic conquest or revolution, the origin and character of which are still matters of speculation. The end of this Arab dynasty is followed by the rise of the Assyrian power, with which Babylon long contended for independence and supremacy, until she recovered both under the properly Chaldean dynasty of Nabopolassar. This dynasty is believed to have reestablished the predominance of the southern tribes of Babylonia, while the Semitic languages of Babylonia and Assyria remained the prevailing languages of the empire. (See Assyria, Babylon, Babylonia, Cuneiform Inscriptions, and the authorities referred to under those heads.)