Most of what is known about the Mahavihara comes from the Mahavamsa, and the Mahavamsa was composed in the Mahavihara tradition. It gives the monastery its foundation by King Devanampiya Tissa for Mahinda in the Mahamegha park, records the planting of the cutting of the Bodhi tree brought from India by Sanghamitta, and narrates the long rivalry with the Abhayagiri from the Mahavihara's point of view.
Wilhelm Geiger's translation made it available to modern scholarship, and it remains an indispensable source for the political and religious history of the island because there is nothing else of comparable range. It is also an interested witness, and the atlas records it as one. The Abhayagiri produced its own literature and that literature does not survive, so the account of a centuries long dispute exists only in the words of the side that won.
Modern scholarship reads the chronicle accordingly, using it as evidence while discounting its evaluations, and the same caution applies to its treatment of kings, who are praised or condemned largely according to their generosity to the Mahavihara. The atlas notes the asymmetry wherever it relies on the chronicle. It is worth adding that the Mahavamsa has had a substantial modern political afterlife in Sri Lanka, where its narrative has been drawn on in arguments about the relationship between Buddhism, the island and its populations, and the atlas records the text as a historical source and those later uses of it as a separate matter.