Only because Assyria conquered and enslaved them. And don't forget they were enslaved by Egypt, enslaved by Babylon, then were only part of Persia because Persia conquered Babylon, likewise ended up property of Alexander after he conquered Persia, then after the Wars of the Diadochi they ended up as the backwater frontier province that Seleucid and Ptolomaic armies kept stomping through.
Only because Assyria conquered and enslaved them. And don't forget they were enslaved by Egypt, enslaved by Babylon, then were only part of Persia because Persia conquered Babylon, likewise ended up property of Alexander after he conquered Persia, then after the Wars of the Diadochi they ended up as the backwater frontier province that Seleucid and Ptolomaic armies kept stomping through.