(Pāli: “explanation”), commentaries on the Pāli Buddhist canon that provide much information on the society, culture, and religious history of ancient India and Ceylon (Sri Lanka). The earliest commentaries, written in Pāli, may have reached Ceylon along with the canon itself by the 3rd century BC. Between then and the 1st century AD they were translated into Sinhalese, and others were written in that language. In the 5th century the greatest commentator, Buddhaghosa, produced a reworking in Pāli of much of the earlier material plus Dravidian commentaries and Sinhalese traditions. Within a century or two, others, notably Dhammapāla, produced similar works on parts of the canon that Buddhaghosa had not covered.

The earlier aṭṭhakathā have not survived, but the works of Buddhaghosa and his successors are mines of information on the development of life and thought in the Theravāda Buddhist community and provide much secular and legendary material as well. Doctrinally orthodox and stylistically elegant, they offer section-by-section philological and exegetical commentary, a critical comparison of various authorities, and lucid narrative.

These commentaries were themselves the subject of later commentaries known as ṭīkā (“commentary”), and these in turn by others called anuṭīkā (“further commentary”). The earlier aṭṭhakathā also served as sources for the epic chronicles of Ceylon, the Dīpavaṃsa (“History of the Island”) and Mahāvaṃsa (“Great History”).