Mbh 5.156.1d

And of foot-soldiers, there were hundreds of thousands of diverse mien, accoutred in armours of diverse kinds and armed also with weapons of diverse species, and decked with golden ornaments. And unto each car, were assigned ten elephants, and unto each elephant ten horses, and unto each horse ten foot-soldiers, as protectors. Again, a large body of troops was kept as a reserve for rallying the ranks that would be broken. And this reserve consisted of cars, unto each of which were attached fifty elephants; and unto each elephant were attached a hundred horses; and unto each horse were attached seven foot-soldiers. Five hundred cars, as many elephants (fifteen hundred horses, and two thousand five hundred foot-soldiers) constitute a Sena. Ten Senas constitute a Pritana; and ten Pritanas, a Vahini. In common parlance, however, the words Sena, Vahini, Pritana, Dhwajini, Chamu, Akshauhini, and Varuthini are used in the same sense.