The primary indigenous religion of the Dayaks is called Kaharingan.
Kaharingan is a form of animism which is categorized as a form of Hinduism in Indonesia.
The practice of Kaharingan differs from group to group and in some instances, when a noble “Kamang” dies, it is believed that the spirit ascends to a mountain where the spirits of past ancestors of the tribe reside. On certain religious occasions, the spirit is believed to descend from the mountain to take part in the celebration.
Over the last 200 years, however, some Dayaks have converted to Islam, abandoning certain cultural rites and practices. Christianity was also introduced by missionaries so that some groups have Christian beliefs systems.