Mohammed did make a change. He organized and controlled the barbarism, while preserving it.
He made all this ancient Arabian barbarism into a rigid system, and added the constraints of law. This is why Islam as interpreted in the strictest manner is legalistic and compassionless. Its also why its so hard to transcend the barbarism.
Unlike Christ, he did not create an Ethics.
Which is just a nice way of saying that the essence of Islam is barbarism or Islam is barbarism codified. It also lays the cause of that squarely at Mohamed's feet which was my point.