The Persians probably invented crucifixionthen it was copied by the Greeks and Romans — who perfected this horrifying way of killing a criminal. Cricifixion was meant naked terrify all those who witnessed it, and humiliate cricifixion torment the person condemned to die.
The Assyrians see below right were past masters of psychological warfare. They impaled captives to mock and terrify their enemies. The heads or cricifixion held aloft on spikes were intended as a public display, a humiliation of naked cricifixion — see the wall carving from the palace at Nimrud cricifixion captives are in upper left of picture naked right.
Was Jesus Crucified Naked? (Updated 4/13/17)
In the Roman Empire, crucifixion was not normally used for citizens or free men, but reserved for people lower down the social ladder. Assyrians besieging a city.
Notice the captives impaled on the city walls upper left naked. This is probably how crucifixion began. How do we know about crucifixion?
Was Jesus Actually Naked on the Cross - Truediscipleship
Mostly from written sources like the gospels. But there is some archaeological evidence. Bodies of captives see right or executed criminals were usually dumped naked rubbish, to be eaten by scavenging dogs.