The Soka Gakkai Dictionary of Buddhism
Abhidharma school[毘曇宗] (Skt; Chin P’i-t’an-tsung; Jpn Bidon-shu)
Also known as the P'i-t'an school. One of the so-called thirteen schools of Chinese Buddhism, the Abhidharma school prospered in northern China during the Northern and Southern Dynasties period (439-589). It based its teachings on abhidharma works such as Dharmashri's Heart of the Abhidharma and Dharmatrata's Supplement to "The Heart of the Abhidharma." Hence the name of the Abhidharma school. P'i-t'an is the Chinese transliteration of abhidharma. The Sanskrit term abhidharma means doctrinal commentary, one of the three divisions of the Buddhist canon, the other two being sutras and vinaya (rules of monastic discipline). The twenty Hinayana schools in India, particularly the Sarvastivada, produced abhidharma works. During the Northern and Southern Dynasties period in China, they were regarded as essential references on Buddhist doctrine. Later in the seventh century, when Hsüan-tsang translated The Dharma Analysis Treasury, The Great Commentary on the Abhidharma, and other abhidharma works into Chinese, the Dharma Analysis Treasury (Chy-she) school absorbed the rapidly declining Abhidharma school.