Ryōkai mandara 両界曼荼羅

Lit. "mandala of the two realms," namely, the *Taizōkai mandara 胎蔵界曼荼羅 described in the Dainichikyō 大日経 (Sk: Vairocanabhisambodhi sutra/Mahavairocana sutra) and the *Kongōkai mandara 金剛界曼荼羅 described in the Kongōchōkyō 金剛頂経 (Diamond Peak Sutra, Sk: Sarva tathaga tatattva samgraha). These two mandala evolved separately in India and entered China by different routes, but in China they subsequently came to be regarded as forming a pair. Hints of the idea that the Dainichikyō and Kongōchōkyō represent complementary systems may already be found in the Chinese translations of Esoteric texts by Bukong (Jp: Fukū 不空, Sk: Amoghavajra; 705-74), but it is thought to have been Huiguo (Jp: Keika 恵果; 746-805), the teacher of *Kūkai 空海 (774-835), who adapted these two mandala to form a pair of religious paintings. Kūkai further developed this concept in his writings, thereby establishing the non-duality of the two divisions ryōbu funi 両部不二, namely, the idea that the Dainichikyō and Kongōchōkyō are complementary systems through the integration of which ultimate truth is revealed . Thenceforth the Ryōkai mandara have been looked upon as the basis of the iconography of Esoteric Buddhism mikkyō 密教 in Japan, and they have exerted considerable influence not only on art, but also on thought and culture.
In Japanese Esoteric Buddhism the Taizōkai mandara is referred to as the "mandala of principle" ri mandara 理曼荼羅 or "mandala of cause" in mandara 因曼荼羅, while the Kongōkai mandara is known as the "mandala of wisdom" chi mandara 智曼荼羅 or "mandala of result" ka mandara 果曼荼羅, and they are customarily hung facing each other in temple halls on the eastern and western walls respectively. The original name of the Taizōkai mandara is Daihitaizōshō mandara 大悲胎蔵生曼荼羅 (mandala born of the womb of great compassion), but once it began being used in conjunction with the Kongōkai mandara, came to be known as the Taizōkai mandara. The term Ryōkai mandara is thought to have been first used by Godai-in Annen 五大院安然 (841-889～898) of the Tendai 天台 sect, and because of its associations with the Tendai sect, there are even today many scholars of the Shingon 真言 sect who instead use the term Ryōbu mandara 両部曼荼羅, or mandala of the two divisions. However, not only is the term Ryōkai mandara widely used by art historians, but it is also used in the designation of national treasures and important cultural properties.
In the Shingon sect, the form of the Taizōkai mandara used in the Ryōkai mandara is that known as the *Genzu mandara 現図曼荼羅, while the form of the Kongōkai mandara used is the *Kue mandara 九会曼荼羅; in the Tendai sect the *Kongōkai hachijūisson mandara 金剛界八十一尊曼荼羅 is sometimes used instead of the Kue mandara. Representative examples of the Ryōkai mandara include the Den shingon-in mandara 伝真言院曼荼羅 at Tōji 東寺 in Kyoto, the Takao mandara 高雄曼荼羅 at Jingoji 神護寺 in Kyoto, and the *Kojima mandara 子島曼荼羅 at Kojimadera 子島寺 in Nara, which have all been designated national treasures, but there are minor differences in the disposition of the deities.