Among the thirty-three masks preserved in the Gallery of Horyu-ji Temple, thirty-one masks are Gigaku masks. They were used for an ancient musical play called Gigaku that was popular in the seventh and eighth centuries. Gigaku was brought from mainland China in the Asuka period (from the end of the sixth century to the first half of the seventh century), but it died out in the Kamakura period (1192-1333), so its actual situation is not certain. More than two hundred and thirty Gigaku masks are now kept in many temples including between one hundred and two hundred masks preserved in Shosoin (the Imperial Repository), most of which are relics of the eighth century. On the other hand, more than half of those preserved in the Gallery of Horyu-ji Temple are likely to date back to the seventh century. They are excellent in their form and thus they are very valuable as Japan's oldest masks.