Bangladesh is noted for the ethnic homogeneity of its population. Over 98 percent of the people are Bengalis, predominantly Bangla-speaking peoples. People speaking Arabic, Persian, and Turkic languages also have contributed to the ethnic characteristics of the region. 

Bangladesh's indigenous population consisted of 897,828 persons, just over 1 percent of the total population, at the time of the 1981 census. They lived primarily in the Chittagong Hills and in the regions of Mymensingh, Sylhet, and Rajshahi. The majority of the tribal population (778,425) lived in rural settings, where many practiced shifting cultivation. Most tribal people were of SinoTibetan descent and had distinctive Mongoloid features. They differed in their social organization, marriage customs, birth and death rites, food, and other social customs from the people of the rest of the country. They spoke Tibeto-Burman languages. In the mid-1980s, the percentage distribution of tribal population by religion was Hindu 24, Buddhist 44, Christian 13, and others 19.

The four largest tribes were the Chakmas, Marmas (or Maghs), Tipperas (or Tipras), and Mros (or Moorangs). The tribes tended to intermingle and could be distinguished from one another more by differences in their dialect, dress, and customs than by tribal cohesion. Only the Chakmas and Marmas displayed formal tribal organization, although all groups contained distinct clans. By far the largest tribe, the Chakmas were of mixed origin but reflected more Bengali influence than any other tribe. Unlike the other tribes, the Chakmas and Marmas generally lived in the highland valleys. Most Chakmas were Buddhists, but some practiced Hinduism or animism.

Of Burmese ancestry, the Marmas regarded Burma as the center of their cultural life. Members of the Marma tribe disliked the more widely used term Maghs, which had come to mean pirates. Although several religions, including Islam, were represented among the Marmas, nearly all of the Marmas were Buddhists.

The Tipperas were nearly all Hindus and accounted for virtually the entire Hindu population of the Chittagong Hills. They had migrated gradually from the northern Chittagong Hills. The northern Tipperas were influenced by Bengali culture. A small southern section known as the Mrungs showed considerably less Bengali influence.

The Mros, considered the original inhabitants of the Chittagong Hills, lived on hilltops and often fortified their villages. They had no written language of their own, but some could read the Burmese and Bangla scripts. Most of them claimed to be Buddhists, but their religious practices were largely animistic.

Tribal groups in other parts of the country included Santals in Rajshahi and Dinajpur, and Khasis, Garos, and Khajons in Mymensingh and Sylhet regions. Primarily poor peasants, these people all belonged to groups in the adjoining tribal areas of India.