Kośa school 
A minor school of Buddhism during its early period in China, which focused on the study of the Abhidharma-kośa by the Indian sage Vasubandhu, translated into Chinese by Paramārtha between 563 and 567. This text, usually seen by the Chinese as a Hīnayāna work, was Vasubandhu's attempt to synthesize the Abhidharma thought of the Sarvāstivāda school of north India, and deals with all aspects of Buddhist psychology and metaphysics. The school always had a tenuous existence, and by 703 the imperial court registered specialists in this text as belonging to the Fa-hsiang school. However, it did flourish during a time when Japan actively sought Buddhist teachings and texts, and it was transmitted to that country as the ‘Kusha school’, one of the Six Schools of Nara Buddhism.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)