Charles Hope in his book "A Horseman's Manual" claims that early Assyrian horsemen rode near the rear, a claim that is repeated on wikipedia as "However, these riders sat far back on their horses, a precarious position for moving quickly, and the horses were held by a handler on the ground, keeping the archer free to use the bow. Thus, these archers were more a type of mounted infantry than true cavalry"

Were there any major differences, beyond the lack of stirrups, in ancient horseback riding?