This example seems to be a copy of one in the Horyuji Collection which dates back to the 8th century.
Gigaku is considered the oldest form of dance performance with masks in Japan and was imported from the continent as early as the 7th century A.D. In its original form Gigaku almost totally vanished at the end of the 12th century or was possibly integrated in Bugaku, the new mask entertainment favoured by the aristocracy.
A substantial number of Gigaku masks survived in some temples in Nara. However, very little information on the performance has come down to us. Therefore one guesses that Gigaku was a sort of procession within a Buddhist ritual accompanied by music and singing and interrupted from time to time by small interludes of humorous or slightly obscene character.
The Gigaku-masks that cover the whole head are oversized (ca. 40cm. long) and their facial expressions, sometimes with distorted features, long noses and round eyes, point to Central Asia and further west as their place of origin.