Since the synod held in Rajagrha for the collection and fixing of the words that was bequeathed by the Buddha and editing them into scriptures, arguments arose among the clerics that led to the seperation of the Sangha. From that time onward，different schools of Hinayana Buddhist were established. As time passed，a certain school would also serperated into different sects. This article shows that among the totally of eoghteen Hinayana sects, seven of them were established during the regime of King `Asoka`.
After King `Asoka`，who united India and become converted to Buddhism，he dispatched missionaries to the neighbouring countries, in four directions, in order to spread the Buddha's teaching. When the monk-missionaries had arrived in the foreign lands, they probably were influenced by the new environment. Due to the foreign culture，new ideas of Buddhism were created. Therefore，the above-mentioned seven Hinayana sects were formed.
This article should also discusses the sources from were the eighteen Hinayana sects derived:
The `Mahisasaka` Sect，the Dharmaguptaka Sect, the Haimavata Sect and the `Tamrasatiya` Sect were derived from the Arya-Sthavira School.
The Mula-Mahasamghika Sect，the Lokottarvadin Sect，the Kukktika Sect，the Bahusrutiya Sect，the `Prajnaptivadin` Sect and the Caitika Sect were derived from the Mahasamghika School.
The Vatsiputriya Sect，the Dharmottariya Sect, the Bhadrayaniya Sect，the sannagarika Sect and the Sammatiya Sect were derived from the Arya- Vatsiputriya School.
The Mula-Sarvastivadin Sect，the Kasyapiya Sect and the Samkrantivadin Sect were derived from the Arya-Sarvastivadin School.
As to the Dharma transmission of the different sects, this article demonstrates that some of them were the religious descendants of Mahakasyapa and Ananda. While the others, however，were descendants of Upali，Aniruddha, Sariptutra and Rahula, and of Katyayana, etc.
