but during this attempt, an over-zealous minister ends up killing some real monks. The king then invites the elder monk Moggaliputta-Tissa, to help him expel non-Buddhists from the monastery founded by him at Pataliputra. 60,000 monks (bhikkhus) convicted of being heretical are de-frocked in the ensuing process. The uposatha ceremony is then held, and Tissa subsequently organises the Third Buddhist council, during the 17th regnal year of Ashoka. Tissa compiles Kathavatthu, a text that reaffirms Theravadin orthodoxy on several points. The North Indian tradition makes no mention of these events, which has led to doubts about the historicity of the Third Buddhist council. Richard Gombrich argues that the non-corroboration of this story by inscriptional evidence cannot be used to dismiss it as completely unhistorical, as several of Ashoka's inscriptions may have been lost. Gombrich also argues that Asohka's inscriptions prove that he was interested in maintaining the "unanimity and purity" of the Sangha. For example, in his Minor Rock Edict 3, Ashoka recommends the members of the Sangha to study certain texts (most of which remain unidentified). Similarly, in an inscription found at Sanchi, Sarnath, and Kosam, Ashoka mandates that the dissident members of the sangha should be expelled, and expresses his desire to the Sangha remain united and flourish. The 8th century Buddhist pilgrim Yijing records another story about Ashoka's involvement in the Buddhist sangha. According to this story, the earlier king Bimbisara, who was a contemporary of the Gautama Buddha, once saw 18 fragments of a cloth and a stick in a dream. The Buddha interpreted the dream to mean that his philosophy would be divided into 18 schools after his death, and predicted that a king called Ashoka would unite these schools over a hundred years later. Buddhist missions In the Sri Lankan tradition, Moggaliputta-Tissa – who is patronised by Ashoka – sends out nine Buddhist missions to spread Buddhism in the "border areas" in . This tradition does not credit Ashoka directly with sending these missions. Each mission comprises five monks, and is headed by an elder. To Sri Lanka, he sent his own son Mahinda, accompanied by four other Theras – Itthiya, Uttiya, Sambala and Bhaddasala. Next, with Moggaliputta-Tissa's help, Ashoka sent Buddhist missionaries to distant regions such as Kashmir, Gandhara, Himalayas, the land of the Yonas (Greeks), Maharashtra, Suvannabhumi, and Sri Lanka. The Sri Lankan tradition dates these missions to Ashoka's 18th regnal year,