4. the mountains--namely, which separate Media and Assyria, and on
one of which the banner to rally the hosts is supposed to be reared.
tumultuous noise--The Babylonians are vividly depicted as hearing
some unwonted sound like the din of a host; they try to distinguish the
sounds, but can only perceive a tumultuous noise.
nations--Medes, Persians, and Armenians composed Cyrus' army.
JFB.
Picture Study Bible