According to the Wen ti-yu ching, or The Sutra Asking About the Nether World, before he became the Lord of Hades Yama was the King of Vaisali.
神話中描述日神變成一匹神馬，和沙娜女神結合，產生了凡間第一個人，這個人的品行最為善良正直，他死後即變成鬼魂的君主和裁判。