Vine Deloria Jr., a member of the Standing Rock Sioux Tribe who was one the nation's most influential scholars, died on Sunday. He was 72.

As best-selling author, Deloria spoke authoritatively on tribal sovereignty and self-determination. As a historian, he promoted Native science amid conflicting Western views. And as an advocate, he worked on countless initiatives, legislative and otherwise, to protect sacred sites, ancestral remains and artifacts and the federal-tribal relationship.

"I cannot think of any words I could possibly say that even begin to capture the significance of this man and his work among Native people and on our behalf for the past half century," Richard West Jr., the director of the National Museum of the American Indian, said in a message quoted by Indian Country Today.

"If you mark down the great figures of the American West in recent times, he belongs there because of his role in reshaping Indian country," Charles F. Wilkinson, a professor of law at the University of Colorado, said in a statement "I think in the last 100 years, he's been the most important person in Indian affairs, period."

"Vine Deloria Jr. has added more to the public understanding of Native people than any other leader of his time," Wilma Mankiller, the first woman principal chief of the Cherokee Nation, wrote in ICT earlier this year.

Deloria was born in 1933 in Martin, South Dakota, near the Pine Ridge (Oglala Sioux) Reservation. His father was Vine Deloria Sr., a descendant of Sitting Bull. The family had a background in religion and were considered leading Indian Episcopalians. Deloria Sr. was an ordained Episcopalian priest as was his father, Philip DeLoria, who was one of the first Sioux tribal members to become an Episcopal priest.

Religion proved to be a strong theme in Deloria's life. After serving in the U.S. Marines, he obtained a master's in theology from the Lutheran School of Theology in Illinois in 1963.

The following year, in 1964, he joined the National Congress of American Indians as its executive director. For three years, until 1967, he worked to reverse the federal government's termination policy. "It threw a real chill in Indian Country," he said in a video message delivered at NCAI's annual conference in 2004, noting that the policy was so poorly developed that Congress once offered to move 10,000 Turtle Mountain Chippewas from North Dakota to Minneapolis and find them jobs.

NCAI's job, he said, was to point out the "illogical" consequences of the policy, while fighting members of Congress who promised to save bigger tribes from termination in exchange for eliminating small tribes in California and elsewhere. NCAI's answer was always a firm no, he recalled. His work on the issue set the stage for another one that has remained in place ever since: self-determination.

In 1969, Deloria published his first book, "Custer Died for Your Sins." A bestseller, it turned him into a national figure and symbol of the burgeoning, and often tumultuous, Native rights movement. Subtitled "An Indian Manifesto," the book helped change the public's consciousness towards American Indians.

The decade following "Custer's" publication saw the enactment of a series of landmark laws that gave tribes greater control over their affairs, led to the return of millions of acres of tribal land, established the national tribal college structure and reaffirmed the United States' treaty and trust obligations to Native people.

In 1970, Deloria obtained a degree in law from the University of Colorado and thus began his lifelong affiliation with the school. He served as a professor of history up until his retirement in 2000 and continued to remain a visible member of Indian community in the Denver and Boulder areas. He gave his papers to the Denver Public Library lived just east of Denver, in Golden, up until his passing. He also helped to establish the Native American Rights Fund, located in Boulder, in 1970.

Deloria eventually wrote more than 20 books, including "God is Red" in 1973, which advocated for the return to traditional ways, and "Tribes, Treaties, and Constitutional Tribulations" a 1999 book that traced more than 200 years of Indian legal and policy developments.

With the publication of "Red Earth, White Lies: Native Americans and the Myth of Scientific Fact" in 1997, Deloria turned his eyes towards prevailing scientific views of the peopling of the Americas. He forcefully, but humorously, derailed the theory that all of the ancestors of American Indians came across the Bering Strait.

The book was indicative of Deloria's ability to challenge Western notions in a way that gave prominence to Native thought. His efforts led to the passage of the Native American Graves Protection and Repatriation Act in 1990 and the 1989 law that authorized the creation of the National Museum of the American Indian, which opened in Washington, D.C., in September 2004.

"Many aspects of federal Indian law would not have developed in as positive a direction as they have without his foresight and guidance. Certainly this is true of Indian education, repatriation and the modern exercise of sovereignty. ICT columnist Suzan Shown Harjo wrote.

She added: "He encourages Native and non-Native people to respect and learn from indigenous traditional knowledge, the wisdom of which is more apparent with each major environmental catastrophe and with each new discovery of Indians by Western science."

Deloria was showered with many accolades during his life. One of the most recent was the American Indian Visionary Award from the ICT newspaper, for his life of achievement.

"In Indian country the name Vine Deloria Jr. is a household word," his niece, Faith Spotted Eagle, wrote. "His quotes are on walls and often roll off the tongues of young Natives doing reports and speeches. Most importantly, he writes what we all would like to say. I read somewhere that someone said that an act of genius ''is saying what we are all thinking.''

"That is what Uncle Vine does," she said. "He speaks for a nation of Natives."