The reciters of the Majjhimanikāya (q.v.), those who learned it and handed it down, probably the “school” of Sāriputta.
This “school” included the Cariyāpiṭaka, Apadāna and Buddhavaṃsa in the Khuddakanikāya, and ascribed the whole Nikāya to the Sutta Piṭaka. DA.i.15; Mil.341.