Easton's Bible Dictionary 
Jeremiah 50:10 51:24,35
The country so named is 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 breadth. "In former days the vast plains of Babylon were nourished by a complicated system of canals and water-courses, which spread over the surface of the country like a network. The wants of a teeming population were supplied by a rich soil, not less bountiful than that on the banks of the Egyptian Nile. Like islands rising from a golden sea of waving corn stood frequent groves of palm-trees and pleasant gardens, affording to the idler or traveller their grateful and highly-valued shade. Crowds of passengers hurried along the dusty roads to and from the busy city. The land was rich in corn and wine."
Recent discoveries, more especially in Babylonia, have thrown much light on the history of the Hebrew patriarchs, and have illustrated or confirmed the Biblical narrative in many points. The ancestor of the Hebrew people, Abram, was, we are told, born at "Ur of the Chaldees." "Chaldees" is a mistranslation of the Hebrew Kasdim , Kasdim being the Old Testament name of the Babylonians, while the Chaldees were a tribe who lived on the shores of the Persian Gulf, and did not become a part of the Babylonian population till the time of Hezekiah. Ur was one of the oldest and most famous of the Babylonian cities. Its site is now called Mugheir, or Mugayyar, on the western bank of the Euphrates, in Southern Babylonia. About a century before the birth of Abram 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 Abram 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 Khammu-rabi. (See Babylon; Abraham; Amraphel .)
Bridgeway Bible Dictionary 
Ancient Babylonia was occupied largely by people belonging to two racial groups, the Sumerians and the Amorites. In addition smaller tribal groups were scattered throughout the region. The most important of the smaller groups were the Chaldeans, who lived in the south of Babylon around the lower reaches of the Euphrates and Tigris Rivers.
In the time before Abraham, the Babylonian rulers were mainly of Sumerian descent and their capital was the Chaldean city of Ur, from which Abraham originally came ( Genesis 11:28; Acts 7:4). About 2000 BC Babylonians of Amorite descent overthrew the dynasty in Ur and established a new capital at the city of Babylon. (For a map of the region and further details of Babylon’s history see Babylon .)
Many centuries later, during the period covered by the biblical books of Kings, a Babylonian of Chaldean descent seized the throne in Babylon (about 720 BC). Chaldeans continued to rule till Babylon was overthrown by Persia in 539 BC. As a result of this Chaldean domination, the practice arose of using ‘Chaldea’ as a name for the land of Babylon as a whole, and ‘Chaldeans’ as a name for Babylonians in general ( Isaiah 13:19; Isaiah 47:1; Isaiah 48:14; Isaiah 48:20; Jeremiah 25:12; Daniel 5:30; Daniel 9:1).
The word ‘Chaldeans’ had also a more technical meaning, which had passed down from ancient times when certain Chaldeans became famous as astrologers, priests and wise men. This is the sense in which the Bible uses the name in the expression ‘magicians, enchanters, Chaldeans and astrologers’ ( Daniel 4:7; Daniel 5:7; Daniel 5:11).
Smith's Bible Dictionary 
Chalde'a. More correctly Chaldae'A , the ancient name of a country of Asia bordering on the Persian Gulf. Chaldea proper was the southern part of Babylonia, and is used, in Scripture, to signify that vast alluvial plain which has been formed by the deposits of the Euphrates and the Tigris. This extraordinary flat, unbroken except by the works of man, extends for a distance of 400 miles along the course of the rivers, and is, on an average, about 100 miles in width.
In addition to natural advantages, these plains were nourished by a complicated system of canals, and vegetation flourished bountifully. Chaldea is said to be the only country in the world where wheat grows wild. Herodotus declared, (i. 193), that grain commonly returned two hundred fold to the sower, and occasionally, three hundred fold.
Cities. - Babylonia has long been celebrated for the number and antiquity of its cities. The most important of those which have been identified are Borsippa ( Birs-Nimrun ), Sippara or Sepharvaim ( Mosaib ), Cutha ( Ibrahim ), Calneh ( Niffer ), Erech ( Warka ), Ur ( Mugheir ), Chilmad ( Kalwadha ), Larancha ( Senkereh ), Is (Hit ), Durabe ( Akkerkuf ); but besides these, there were a multitude of others, the sites of which have not been determined.
Present condition. - This land, once so rich in corn and wine, is to-day, but a mass of mounds, "an arid waste; the dense population of former times is vanished, and no man dwells there." The Hebrew prophets applied the term, "land of the Chaldeans," to all Babylonia and, "Chaldeans," to all the subjects of the Babylonian empire.
Holman Bible Dictionary 
The Chaldeans In Old Testament times different peoples occupied southeastern Mesopotamia at various times. One such group was the Chaldeans, whose name derives from the ancient term Kaldai , which refers to several Aramean tribes who moved into lower Mesopotamia between 1000,900 B.C. Their new homeland was a flat, alluvial plain of few natural resources, many marshes, spring flooding, and very hot summers.
Relation to Babylonia At first the Chaldeans lived in tribal settlements, rejecting the urban society of the Babylonians to the northwest—so-called after the leading city-state of the region, Babylon, to which the Old Testament refers over 300 times. Babylon was once the capital city of the great King Hammurabi (ca. 1763-1750 B.C.), remembered for the empire he created, and for the famous law code which bears his name.
As time passed, the Chaldeans gradually acquired domination in Babylonia. In the process they also took on the title “Babylonians,” or more exactly, “Neo-Babylonians.” As a result, the terms Chaldea(ns) and (Neo-) Babylonia(ns) may be used interchangeably ( Ezekiel 1:3 , Rsv, Niv; Ezekiel 12:13 , NIV). See [[History And Religion Of Babylon]] .
In the eighth century B.C., the Chaldeans emerged as the champions of resistance against Assyria, a dangerous, aggressive imperial force in upper Mesopotamia. At this time the Chaldeans begin to appear in the Old Testament, first, as possible allies with Judah against Assyria, but later, as a direct threat to Judah and Jerusalem.
Tony M. Martin
Morrish Bible Dictionary 
This was strictly the southern part of Babylonia, but the many references in scripture to the Chaldeans show that the inhabitants of the whole of Babylonia are alluded to by that name. Perhaps Ur is the only place in Chaldea proper to which scripture definitely refers. This was apparently a maritime city, which agrees with the country extending to the Persian Gulf; but the Gulf has receded far from where the river once joined it. The land of Shinar adjoined Chaldea on the north, in which were the early cities of Babel, Erech, Accad and Calneh. Genesis 10:10 . The whole district was situate between the rivers Tigris and the Euphrates, but extended west of the latter. It was anciently well watered by canals, and is judged to have been productive. Herodotus says mounds, were built where the river once spread like a sea through the whole plain. Now all is desolation, some parts very dry, and others a mere swamp, with lines of mounds in various directions. The prophecies declared that it would be so, but as stated above, they refer to the whole of Babylonia. Jeremiah 1:10; Jeremiah 51:24,35; Ezekiel 11:24; Ezekiel 16:29; Ezekiel 23:15,16 .
Watson's Biblical & Theological Dictionary 
or Babylonia, the country lying on both sides of the Euphrates, of which Babylon was the capital; and extending southward to the Persian Gulf, and northward into Mesopotamia, at least as far as Ur, which is called Ur of the Chaldees. This country had also the name of Shinar. See Babylon .
American Tract Society Bible Dictionary 
A country in Asia, the capital of which, in its widest extent, was Babylon. It was originally of small extent; but the empire being afterwards very much enlarged, the name is generally taken in a more extensive sense, and includes Babylonia, which see.
Hawker's Poor Man's Concordance And Dictionary 
The Nuttall Encyclopedia 
Ancient name for Babylonia.
- Chaldea from Easton's Bible Dictionary
- Chaldea from Bridgeway Bible Dictionary
- Chaldea from Smith's Bible Dictionary
- Chaldea from Holman Bible Dictionary
- Chaldea from Morrish Bible Dictionary
- Chaldea from Watson's Biblical & Theological Dictionary
- Chaldea from American Tract Society Bible Dictionary
- Chaldea from Hawker's Poor Man's Concordance And Dictionary
- Chaldea from The Nuttall Encyclopedia