Kukai brought two mandalas back from China in 806, a gift transmitted to him by his teacher Huiguo shortly before Huiguo's own death, representing the two aspects of ultimate reality that would become the doctrinal core of the Shingon school Kukai founded in Japan. The originals, and a first copy made from them, were kept at To-ji temple in Kyoto, but both have since been lost. What survives instead, and what is now the oldest extant Ryokai mandala anywhere in Japan, is the version held at Jingo-ji temple on Mount Takao, produced at some point within Kukai's own lifetime and understood to closely reproduce the lost original rather than to represent a later reinterpretation of it.
Rather than full color paint, the Jingo-ji mandalas are rendered in gold and silver pigment on purple silk twill damask, each of the two panels, the Kongokai and the Taizokai, measuring nearly four square meters. That scale and material choice alone mark it as an object built for more than passing devotional use. It is the only Ryokai mandala known to have survived from Kukai's own generation, which is what has made it, rather than any later copy, the version museums reach for when they want to show what the earliest Japanese esoteric Buddhist painting actually looked like.