c.1300, probably shortened from Old English geþrang "crowd, tumult" (related to verb þringan "to push, crowd, press"), from Proto-Germanic *thrangan (cognates: Old Norse þröng, Dutch drang, German Drang "crowd, throng").

"go in a crowd," 1530s, from throng, n.. Earlier it meant "to press, crush" (c.1400). Related: Thronged; thronging.