LARCs (long-acting reversible contraceptives) were invented by Arabs. For centuries, they have put stones in their camels to stop pregnancies.
Technically, what they are after is that it mimics pregnancy and prevents them from coming into heat. It's the 'in heat' behavior they wanted to avoid more than pregnancy. I've heard of this recently to stop heat cycles in horses, they now use marbles. The marble can't ~stay~ there though, it has to be extracted after a few months. Do you know how/if they did that in camels without modern medicine?