Acala first appears in the "Amoghapāśakalparāja Sūtra" (不空羂索神変真言經, "Bùkōng juànsuǒ shénbiàn zhēnyán jīng", translated by Bodhiruci circa 707-709 CE), where he is described as a servant or messenger of the buddha Vairocana:The first from the west in the northern quadrant is the acolyte Acala (不動使者). In his left hand he grasps a noose and in his right hand he holds a sword. He is seated in the half-lotus position.More well-known, however, is the following passage from the "Mahāvairocana Tantra" which refers to Acala as one of the deities of the Womb Mandala:Below the lord of mantras Vairocana, in the southwestern direction, is Acala, servant of the Tathāgata (不動如来使). He holds the sword of wisdom and the noose ("pāśa"). His hair hangs on his left shoulder. One eye lightly squinting, he gazes intently. Blazing flames radiate from his awe-inspiring body. He dwells on a large rock. On his forehead are wrinkles like waves on the water. He is a young boy with a plump body.The deity was apparently popular in India during the 8th-9th centuries as evident by the fact that six of the Sanskrit texts translated by the esoteric master Amoghavajra into Chinese are devoted entirely to him.