Free-flowing robes and tunics are as ancient as civilization, but pants are only about 3 or 4 thousand years old and were created by nomadic horse-riding people for pretty obvious and practical reasons. Greeks thought pants-wearers were barbaric, that’s what Persians, Scythians and other Asian people wore. The Romans hated pants, thinking them unsophisticated and a sign of aggressiveness. In 476 when the aggressive and unsophisticated Visigoths sacked Rome and soon pants were worn throughout western civilization.
From:: Who invented pants?