Muscular bare-chested guardians, or lokapala, are derived from Gandharan prototypical depictions of Vajrapani, 'Thunderbolt bearer,' who accompanies the Buddha Sakyamuni and represents the power of the Dharma Law, and who is in turn derived from Hellenistic representations of Herculean or Atlantean figures within architectural friezes and sarcophagi. As the depiction of turning, three-dimensional bodies in stone sculpture became achieved with greater confidence through the Sui to Tang period, the early eighth century examples at Longmen, of which the present head is an example, show these figures almost emerging from, or caught within, the living rock walls. Compare the fine examples flanking the entrance to Cave 29, one of the many subsidiary caves, but among the few left in a better state of preservation, illustrated in Complete Works of Statues in Longmen Grottoes - vol.1 - Binyang Cave, Beijing, 2002, figs. 28 - 30.
Surviving fragments of lokapala are relatively rare, particularly when compared to fragments of Buddha heads, and the fine expressive carving on the present head, as he appears to shout the power of the Law in a great exhalation of prana-breath, compares well with the frequently illustrated head of a lokapala, in a Japanese collection, exhibited at the Osaka Municipal Museum of Art, 'Chinese Buddhist Stone Sculpture. Veneration of the Sublime', 1995, no. 59.