The Guardian Kings, according Buddhist belief, guard the four quarters of the world and protect the Buddhist law. They are said to live on the mythical Mount Meru, at the gates of the paradise of Indra, the protector of Buddhism. The Guardian Kings are acolytes of the Bodhisattva Avalokiteshvara.
Originally, they were regarded as benevolent, but they developed into menacing warriors. They are usually shown wearing armor and helmets or crowns. The kings are said to have assisted at the birth of Gautama Buddha and to have held up the hooves of his horse when he left the palace of his father for the outside world. In Indian art, they are usually shown riding elephants, whereas in Tantrism they are often shown trampling demons.
The Ultimate Encyclopedia of Mythology by Arthur Cotterell and Rachel Storm