Patricia Berger has noted that votive images, particularly those painted on wooden plaques or etched into gilded bronze, were found in great quantities in the region of the Tarim Basin, the Tang and Northern Liao empires, and in the region of Yunnan. This is the sole example known to be etched and inlayed in iron.¹  The exact origin of this plaque is not known; it may in fact be of Tangut manufacture, as certain stylistic similarities can be seen in the facial features when compared with a work of Tangut manufacture. We can also detect the Tang preference for fleshiness in the face and body. But the closest similarities are found when the plaque is placed beside images from the caves of Kizil and Bezeklik that date to the period of Uighur control.

References:

(1) The Asian Art Museum of San Francisco: Selected Works (San Francisco: The Asian Art Museum of San Francisco, 1994), p. 96.