Among the most interesting of those races were the Tharks, a race of green-skinned beings who looked sort of Frog-like in the face, manlike in the body (but very big and strong) and they had four arms! This made for some vicious fighting, with one arm to hold a shield and three others free to wield various sharp weapons. Tharks are a bit like Orcs, I'd say...similar concept...but the 4 arms is really a shocker. There were other creatures with extra sets of legs too, including some huge felines resembling lions.
There was a Thark leader, Tars Tarkas, who became a lifelong friend of John Carter, and fought many battles beside him.