The indigenous tribes of Siberut Island are known as the Mentawai people. The social structure of the Siberut Mentawai people, an egalitarian sociopolitical structure, is a legacy dating back to the neolithic era. Mentawai people are organized into family groups known as Uma, whose egalitarian patrilineal family systems are politically autonomous. Each uma consists of 5 to 10 nuclear families living together, and average 30-60 people.

In 1930, the population on the island of Siberut was estimated at 9000 people. That number has more than tripled. In 2001, the population of Siberut was 31 695 people, with a population density of about 8 persons per km 2. The estimated percentage of the population of productive age (15-55 years) was 62% in 2000. Data in the same year showed that about 70% of the population of Siberut worked as farmers and gatherers of forest products and about 23% worked as a fisherman. The rest worked as clerks and in other service areas. General education level is very low amongst the native population, with an average education level of only elementary school. The majority of residents are indigenous Mentawai and 10% were migrants.

The dominant economic activity in Siberut is forest use. The forest plays an important role as a source of food, medicines and other materials. Siberut’s market network connects local residents with trade in forest products and agricultural products at the global level. The expansion of monotheistic religions has formally replaced local spiritual teachings. Since the early days of Indonesia’s independence, contact with concepts such as the idea of development, nature conservation, and the recent policy of regional autonomy has influenced the process of change. The way in which these concepts are being adopted and are instigating change varies from one area of Siberut to another.