It is not entirely clear whether this object is a chess piece, a small container or a representation of a mythical warrior. Of the alternative explanations, the suggestion that it may be a container arises from the hollow head, designated as if for storing small items. The fact that the horse, which is now headless, is also winged might point to the third interpretation of a mythical warrior. However, as a horseman or charioteer, it might have been used as a chess piece, in which case it would presumably have been a rook or knight.
William Greenwood in [Greenwood 2014]
69. Wilkinson, C.K., and J. McNab Dennis, (1968). Chess: East and West, Past and Present; A Selection from the Gustavus A. Pfeiffer Collection. New York: Metropolitan Museum of Art, no. 3.
[ Farhadi and Anavian Company, New York, until 1965; sold to MMA]
Greenwood, WIlliam. "Board Games from India to Spain." In Kings & Pawns. Doha, Qatar: Museum of Islamic Art, Doha, 2014. pp. 48–49, ill. p. 49.
Linder, Isaac. The Art of Chess Pieces. 1994. Mentions the piece, and assigns it to the 6th or 7th century.
Carboni, Stefano. "Chessmen in the Department of Islamic Art at The Metropolitan Museum of Art." Scacchi e Scienze Applicate suppl. no. 7, fasc. 15 (1996). ill. pp. 2-3 (b/w).