Explanation:

First Buddhist Council was held soon after the death of the Buddha, dated by the majority of recent scholars around 400 BCE, under the patronage of the king Ajatashatru with the monk Mahakasyapa presiding, at Sattapanni caves Rajgriha (now Rajgir). Its objective was to preserve the Buddha's sayings (suttas) and the monastic discipline or rules (Vinaya). The Suttas were recited by Ananda, and the Vinaya was recited by Upali. Western scholarship has suggested that the Abhidhamma Pitaka was likely composed starting after 300 BCE because of differences in language and content from other Sutta literature.
Second Buddhist Council resulted in the first schism in the Sangha. Modern scholars see this event as probably caused by a group of reformists called Sthaviras who split from the conservative majority Mahasa?ghikas. This view is supported by the vinaya texts themselves, as vinayas associated with the Sthaviras do contain more rules than those of the Mahasa?ghika Vinaya.
Third Buddhist Council was convened by the Mauryan king Ashoka at Pataliputra , under the leadership of the monk Moggaliputta Tissa. Its objective was to purify the Buddhist movement, particularly from opportunistic factions which had been attracted by the royal patronage. The king asked the suspect monks what the Buddha taught, and they claimed he taught views such as eternalism, etc., which are condemned in the canonical Brahmajala Sutta. He asked the virtuous monks, and they replied that the Buddha was a "Teacher of Analysis" (Vibhajjavadin), an answer that was confirmed by Moggaliputta Tissa. The Council proceeded to recite the scriptures once more, adding to the canon Moggaliputta Tissa's own book, the Kathavatthu, a discussion of various dissenting Buddhist views now contained in the Theravada Abhidhamma Pitaka. This council seems to have been the cause of the split between the Sarvastivada and the Vibhajjavada schools.
Fourth Buddhist Council was held in the Sarvastivada tradition, said to have been convened by the Kushan emperor Kanishka, in 78 AD at Kundalban in Kashmir. It is said that Kanishka gathered five hundred Bhikkhus in Kashmir, headed by Vasumitra, to systematize the Sarvastivadin Abhidharma texts, which were translated from earlier Prakrit vernacular languages (such as Gandhari in Kharosthi script) into the classical language of Sanskrit.