Fourth Buddhist Council is the name of two separate Buddhist council meetings. The first one was held in the 1st century BCE, in Sri Lanka. In this fourth Buddhist council the Theravadin Pali Canon was for the first time committed to writing, on palm leaves. The second one was held by the Sarvastivada school, in Kashmir around the 1st century CE.
The Fourth Buddhist council of Theravada Buddhism was held at the Anuradhapura Maha Viharaya in Sri Lanka under the patronage of Valagamba of Anuradhapura in 25 BCE, but there is a major inconsistency if this Valagamba of Anuradhapura died in 77 BCE and so was not around to patronize this Council some 52 years later. Norman places the life of this King in the period 29 BCE to 17 BCE which is in stark disagreement to a death year of 77 BCE for Valagamba of Anuradhapura:
The Dipavamsa states that during the reign of Vattagamani Abhaya (29—17 CE.) the monks who had previously remembered the Tipitaka and its commentary orally now wrote them down in books, because of the threat posed by famine, war, and the growing power of the newly established Abhayagiri vihdra, which enjoyed the king's favour. The Mahavamsa also refers briefly to the writing down of the canon and the commentaries at this time
The council was held in response to a year in which the harvests in Sri Lanka were particularly poor and many Buddhist monks subsequently died of starvation. Because the Pāli Canon was at that time oral literature maintained in several recensions by dhammabhāṇakas (dharma reciters), the surviving monks recognized the danger of not writing it down so that even if some of the monks whose duty it was to study and remember parts of the Canon for later generations died, the teachings would not be lost.