The Fourth Council was held in Tambapanni (Sri Lanka) in 29 B.C. under the patronage of King Vattagamani. The main reason for its convening was the realization that it was now not possible for the majority of monks to retain the entire Tipitaka in their memories as had been the case formerly for the Venerable Mahinda and those who followed him soon after. Therefore, as the art of writing had, by this time developed substantially it was thought expedient and necessary to have the entire body of the Buddha's teaching written down.
King Vattagamani supported the monk's idea and a council was held specifically to reduce the Tipitaka in its entirety to writing. Therefore, so that the genuine Dhamma might be lastingly preserved, the Venerable Maharakkhita and five hundred monks recited the words of the Buddha and then wrote them down on palm leaves. This remarkable project took place in a cave called, the Aloka lena, situated in the cleft of an ancient landslip near what is now Matale. Thus the aim of the Council was achieved and the preservation in writing of the authentic Dhamma was ensured. In the Eighteenth Century, King Vijayarajasiha had images of the Buddha created in this cave.
After the Council, palm leaves books appeared, and were taken to the other countries such as Burma, Thailand, Cambodia and Laos.
(The Tipitaka and its commentaries were brought to Sri Lanka by the missionary monk Mahinda of the Third Buddhist Council.)