Ur Kaśdim or Ur of the Chaldees (אוּר כַּשְׂדִים) is a biblical place mentioned in the Book of Genesis that refers to a location that the Patriarch Abraham may have been from. Not only is there much debate in interpreting Ur Kaśdim as Abraham's birthplace, but also identifying this location.
Chaldea or Chaldaea (pron.: /kælˈdiːə/), from Greek Χαλδαία, Chaldaia; Akkadian: māt Ḫaldu; Hebrew: כשדים, Kaśdim; Aramaic: ܟܠܕܘ, Kaldo) was a marshy land located in south eastern Mesopotamia which came to rule Babylon briefly. Tribes of Semitic settlers who arrived in the region from the 10th Century BC became known as the Chaldeans or the Chaldees. The Hebrew Bible uses the term כשדים (Kaśdim) and this is translated as Chaldaeans in the Septuagint.
The short-lived 11th dynasty of the Kings of Babylon (6th century BC) is conventionally known to historians as the Chaldean Dynasty, although only the first four rulers of this dynasty were known to be Chaldeans, and the last ruler, Nabonidus (and his son and regent Belshazzar) was known to be from Assyria. The region in which the Chaldeans settled was in the southern portion of Babylonia, lying chiefly on the right bank of the Euphrates. Though the name came to be commonly used to refer to the whole of southern Mesopotamia, Chaldea proper was in fact the vast plain in the far south east formed by the deposits of the Euphrates and the Tigris, extending to about four hundred miles along the course of these rivers, and about a hundred miles in average width.