Actually I think that’s the biblical boarders for Israel as denoted by God.
Genesis 15.18 says “from the river of Egypt to the great river, the Euphrates.” By the “river of Egypt” is supposed to be meant a wadi in the eastern part of the Sinai peninsula (not far to the west of the current Israeli border). I don’t know of any passage that includes Mesopotamia in the land promised to Abraham’s descendants.
Borders