
Stone
The Ten Kings of Hell are carved to either side of the central figure of Ksitigarbha Bodhisattva on the upper tier of Niche 20. To the right of Ksitigarbha are, from right to left, King Qinguang, King Chujiang, King Songdi, King Wuguan, and King Yama. To the left of Ksitigarbha, from right to left, are King Biancheng, King Taishan, King Pingzheng, King Doushi, and King Zhuanlun. The ten kings and the two officials sit behind tables draped with a cloth bearing their names and various verses. On the far right is the Official of Present Retribution and on the far left is the Official of Quick Retribution. There are scribes attending each king, with appearances similar to actual courtroom attendants at the time.
According to the Sutra on the Ten Kings of Hell, the kings will sentence people to hell unless they cultivate sufficient merits in life by doing good deeds and making offerings to the Triple Gem. In addition, the sutra states that after the death of a relative, a ritual ceremony should be performed every seven days for 49 days, then again after 100 days, after a year, and after three years.
For more details, go to the Encyclopedia of Buddhist Arts: Caves A-E, page 263.