The findings show that the integration and adaptation of Dayak Ngaju religious system adherents to Hinduism was done because of both internal and external factors. The internal factor includes the needs for recognition of their basic rights in religion as well as desire for changes, pioneered by intellectuals and leaders of Dayak Ngaju religious system. The external factor includes religious politics, economy, education, religious conversion, as well as the existence of Great Council of Kaharingan Hinduism and the role of State Hindu College of Tampung Penyang Palangka Raya. The adaptation strategies are indicated through accommodative behaviours, revitalization and revivalization, as well as resistance. The implication of the adaptation strategies is that the adherents of Dayak Ngaju religious system are able to maintain Kaharingan identity by calling the religion “Hindu Kaharingan”, even though in state administration, the religion is still written as Hinduism. In daily practice, the teachings of Dayak Ngaju religious system can be delivered in its entirety, and the adherents may still have their rights in religious practices, education, economy, and politics just like the adherents of Indonesian official religions.