
Clay
In the main chamber of Cave 55, three groups of statues are placed upon a U-shaped central altar that extends out from the back (west), south, and north walls. The groups represent the three major assemblies of Maitreya.
The central figure in each group of statues is Maitreya Buddha, sitting on a throne with legs pendent and feet resting on lotus pedestals. The Buddhas have usnisas, round faces, and necks marked with three lines. Their layered robes hang in curving folds. The Maitreya on the back wall has an urna between the eyebrows and smiles gently. The raised right hand probably forms the vitarka (teaching) mudra, while the left hand rests on the knee. This Maitreya is flanked by a disciple and a Heavenly King, both standing on lotus pedestals. The disciple on the right is gaunt and aged, with visible ribs and a solemn face, identifying him as Mahakasyapa, foremost in ascetic practices. The Heavenly King on the left appears proud and courageous. The Maitreya Buddhas on the north and south walls have attendant Bodhisattvas at their sides.
For more details, go to the Encyclopedia of Buddhist Arts: Caves M-Mo, page 875.