Transeuphratean

adjective1

1. •
   Of or relating to the lands west of the Euphrates that were incorporated into the Assyrian, Babylonian and later Achaemenid province of Eber-Nari (from Akkadian meaning 'Beyond the River, i.e. the Euphrates').

   • The reference to the Transeuphratean nations is much more likely […] — 1848