What act of congress again encouraged the formation and power if tribal government?

The Indian Self-Determination and Education Assistance Act of 1975 encouraged the formation and power of tribal governments by allowing tribes to take greater control over their own affairs, including education and social services. This act enabled tribes to negotiate contracts with the federal government to administer programs and services, promoting self-governance and autonomy. As a result, tribal governments gained more authority and resources to address the needs of their communities.