Asian elephants were an integral part of warfare in Thailand. They would commonly be mounted by higher-ranking warriors like generals or royalty. To choose a successor to Intaraja I, his two sons fought on elephants. Krabi–krabong was often practiced by the palace mahouts or elephant trainers. From the back of an elephant, archers could shoot arrows at enemies below or, if he was wielding a polearm, engage in hand-to-hand combat with another mounted fighter. After the 15th-century introduction of gunpowder, elephants served as tanks with cannons mounted on their backs. The legs were the war-elephant's weak spot, so they had to be guarded by up to four foot soldiers. Although mahouts no longer practice martial arts, reenactments of such battles are staged by performers who are often from families that have been training elephants since the Ayutthaya Kingdom.