Theravada Sangha a group of Bhiksus who follow the theravada school of buddhism. The Bhiksus of Bangladesh are followers of this school and this is why they are collectively called Theravada Sangha. Their life and activities are regulated by Vinayapitaka, which contains detailed guidance for Bhiksus.
It was due to the patronage of Emperor Ashoka and the ardent efforts of his son Mahendra that Buddhism spread far beyond the borders of India. In course of time local cultures influenced the religious rites of the followers of Buddhism. This also influenced the Bhiksus and they started following mixed practices in place of the original practices. They started calling themselves mahasanghik or reformist Buddhists. Out of this mahasanghik stream emerged various schools of Buddhist thought. But the Buddhists of Bangladesh and many other Asian countries still follow the practices of the original school. They are collectively called Theravada Sangha or Hinayana Sangha.
Although the Bhiksus of Bangladesh are collectively known as Theravada Sangha and strictly follow its practices, there are several divisions among them because of different gurus. These divisions are known as nikaya. Nikaya divisions are found in Bangladesh and many other Asian countries. Among the well-known nikayas in Bangladesh are Mahasthavira nikaya, Sangharaja nikaya, Sudharma nikaya and Dohara or Doyara nikaya. The followers of Mahasthavira and Sangharaja nikayas are mostly Bengali Buddhists from the plains, with Mahasthavira nikaya being the older of the two. The Sangharaja nikaya was established in 1864 under the leadership of Sangharaja Saramedha Mahasthavira. Tribal Buddhists predominate in Sudharma and Dohara nikayas. The followers of these two schools live in Cox's Bazar, Ramu, Teknaf and other areas of the Chittagong Hill Tracts. In matters of religious practices Mahasthavira and Sangharaja are almost identical. The practices followed by the Sudharma and Dohara nikayas are also very close to each other. [Suman Kanti Barua]