It was originally Kubera from Hinduism in India, which has become Vaishuravana (Tamonten) as a Buddhism deity and is called Bishamonten in Japan.
元はインドのヒンドゥー教のクヴェーラ神で、これが仏教の神のヴァイシュラヴァナ（多聞天）になり日本では毘沙門天と呼ばれる。