The term “six schools of the southern capital” 南都六宗 refers to the mainstream and officially recognized Buddhist schools that flourished in the capital Heijō-kyō 平城京 (Nara) during the Nara period (710 to 794) in contrast to the “northern capital” of Heian-kyō 平安京 (Kyōto). The term itself seems to have been devised at a later time to contrast it with the two later schools of Tendai and Shingon which gained enormous followings in the Heian period (794-1185). Whereas these two were more practice-oriented, the six schools are now understood as having been more scholastic. All of these stand in contrast to the popular Pure Land and Nichiren movements during the Kamakura period (1185–1333) which were highly accessible to common folk. However, there is early mention of “five schools” which excluded Kegon. For example, in 718 there is a government document which mentions “five schools” and the “teachings of the Tripiṭaka".
The six schools are as follows:
- Sanron-shū 三論宗
- Jōjitsu-shū 成實宗
- Hossō-shū 法相宗
- Kusha-shū 倶舎宗
- Ris'shū 律宗
- Kegon-shū 華嚴宗
These largely represent the prevailing intellectual Buddhist currents that were mainstream during the early to mid Tang period (618-907). The Japanese adopted Buddhism through various channels, at first through contacts with Korean kingdoms. In particular was the Yamato court's ally Paekche (for details see the following: http://huayanzang.blogspot.com/2013/03/ ... japan.html
Japan is unique in East Asia for having remarkably preserved the material and intellectual components of these six schools. Physical specimens such as handwritten manuscripts, temples and statues dating back to the Nara period are readily visible in Nara today (see http://huayanzang.blogspot.com/2013/07/ ... ttvas.html
). Japan also preserved many manuscripts that were lost on the mainland and only later recovered.
The term rendered “school” here was initially represented in Japan with the Chinese character shū 衆 (assembly), whereas after around the completion of the Daibutsu 大佛 at Tōdai-ji 東大寺 in 752, the character shū 宗 (sect) came to be employed. The essential difference was that the former was a gathering of scholars committed to common research whereas the former reflects more exclusive ecclesiastical communities. In general multiple communities could reside within the same temple, whereas from the Heian period it tended to be “one temple, one sect”.
Saichō 最澄 (767–822) consciously detached himself from Nara to build his own exclusive Tendai school based on Mount Hiei, a topic which I explored in an article Saichō's Monastic Reforms (see here: https://sites.google.com/site/dharmadep ... os-reforms
). His contemporary Kūkai 空海 (774-835) likewise formed an exclusive new tradition, however Ryūichi Abe does state "that at the heart of Kūkai's effort to disseminate Esoteric Buddhism in Japan was not the establishment of a sect but the creation of a new type of religious discourse grounded in his analysis of the ritual language of mantra."
Abe Ryūchi, The Weaving of Mantra: Kūkai and the Construction of Buddhist Esoteric Discourse
(New York: Columbia University Press, 1999), 4.
Nevertheless, Shingon did become multiple exclusive sects, and Heian period Buddhism is characterized by a sectarian consciousness which was only amplified in later centuries.
If you want a good introduction to the six schools of Nara Buddhism (as included in the eight schools which further add Shingon and Tendai), then you should read Gyōnen's work written in the Kamakura period. It is available in translation:The Essentials of the Eight Traditions
http://www.bdkamerica.org/default.aspx? ... nguageid=1
Composed by Gyōnen Extracanonical work This “Essentials of the Eight Schools” gives a concise account of the history and doctrines of the eight principal Buddhist -schools in existence in Japan at the time of the author, i.e. the six schools which were introduced to Japan during the Nara Period and the two schools introduced by Saichō and Kūkai during the Heian Period. This work may thus be described as an introduction to Japanese Buddhism. Fascicle 1 contains a preface and accounts of the Kusha, Jōjitsu and Discipline Schools, and Fascicle 2 deals with the Hossō, Sanron, Tendai, Kegon and Shingon Schools, followed by brief comments on the Zen and Pure Land Schools. The work takes the format of questions and answers, discussing such subjects as the name, basic scriptures, lines of transmission, and doctrines of each school. Since a brief history of the transmission of Buddhism from India via China to Japan is also included, it serves in fact as a very handy exposition of Japanese Buddhism.