Latin word turba comes from Proto-Indo-European *(s)tur-

Detailed word origin of turba

Dictionary entry	Language	Definition
*(s)tur-	Proto-Indo-European (ine-pro)	to rotate, twirl, swirl, move
τύρβη	Ancient Greek (to 1453) (grc)
turba	Latin (lat)	Mob, crowd, throng. Multitude. Stir, disturbance, tumult, uproar, trouble.