The principal repositories of Sinhalese tradition are the Dipavamsa, the Mahavamsa, and the historical preface of Buddhaghosa’s Samanta-pasadika. [20] All later works are founded on these three, so far as concerns the conversion of Ceylon and the immediately subsequent period, and the three works appear to be rearrangements of a single source known as the Atthakatha, Sihalatthakatha, or the words of the Porana (ancients).  These names were given to commentaries on the Tipitaka written in Sinhalese prose interspersed with Pali verse and several of the greater monasteries had their own editions of them, including a definite historical section.[21] It is probable that at the beginning of the fifth century A.D. and perhaps in the fourth century the old Sinhalese in which the prose parts of the Atthakatha were written was growing unintelligible, and that it was becoming more and more the fashion to use Pali as the language of ecclesiastical literature, for at least three writers set themselves to turn part of the traditions not into the vernacular but into Pali.  The earliest and least artistic is the unknown author of the short chronicle called Dipavamsa, who wrote between 302 A.D. and 430 A.D.[22] His work is weak both as a specimen of Pali and as a narrative and he probably did little but patch together the Pali verses occurring from time to time in the Sinhalese prose of the Atthakatha.  Somewhat later, towards the end of the fifth century, a certain Mahanama arranged the materials out of which the Dipavamsa had been formed in a more consecutive and artistic form, combining ecclesiastical and popular legends.[23] His work, known as the Mahavamsa, does not end with the reign of Elara, like the Dipavamsa, but describes in 15 more chapters the exploits of Dutthagamani and his successors ending with Mahasena.[24] The third writer, Buddhaghosa, apparently lived between the authors of the two chronicles.  His voluminous literary activity will demand our attention later but so far as history is concerned his narrative is closely parallel to the Mahavamsa.[25]

The historical narrative is similar in all three works.  After the Council of Pataliputra, Moggaliputta, who had presided over it, came to the conclusion that the time had come to despatch missionaries to convert foreign countries.  Sinhalese tradition represents this decision as emanating from Moggaliputta whereas the inscriptions of Asoka imply that the king himself initiated the momentous project.  But the difference is small.  We cannot now tell to whom the great idea first occurred but it must have been carried out by the clergy with the assistance of Asoka, the apostle selected for Ceylon was his[26] near relative Mahinda who according to the traditions of the Sinhalese made his way to their island through the air with six companions.  The account of Hsuan Chuang hints at a less miraculous mode of progression for he speaks of a monastery built by Mahinda somewhere near Tanjore.