The old Commentary on the Tipiṭaka, which contained the Mahāvihāra tradition.
It was supposed to have been compiled by, or at least under, Mahinda.
Buddhaghosa learnt it under Saṅghapāla and retranslated it into the Magadha (Pāḷi) tongue, while living in the Ganthākara-
It evidently contained a great deal of historical material as well. For its nature and contents see MT. Introd. lvii ﬀ.