The book of Ezra is written in Hebrew, but one of its most
frequently-used expressions is not Hebrew but Aramaic.
The words `abar nÄ•har are translated “beyond the river” or “this side of the river” in most of our
Bibles. They occur in the sections of Ezra that contain letters written by the
enemies of the returning Jewish exiles in Jerusalem to kings of the Medo-Persian
empire, and by the functionaries of these kings in response, since Aramaic
was the language in which royal edicts were issued. The expression also occurs,
probably for the sake of consistency, in the Hebrew narrative portions of Ezra
which have to do with the contents of the letters.
Basically, “beyond the river”
means the biblical land of Israel and any of the surrounding nations over which
Israel, at the height of its powers, had influence.