(CNN)Peterson Zah, who led the Navajo Nation as chairman and its first president, died earlier this week, according to tribal leaders. He was 85.
"It's a big loss for the Navajo Nation. I want to let Indian Country know, as well. He was a huge tribal advocate across Indian Country and America. Thank you to his family for letting us have him lead the Navajo Nation," Navajo Nation President Buu Nygren said in a statement.
Zah died Tuesday surrounded by family at the Tséhootsooí Medical Center in Fort Defiance, Arizona, after he had been "ill for some time," according to a joint statement by the Navajo Nation Office of the President and Vice President and the Navajo Nation Office of the Speaker.
In 1990, Zah became the first elected president of the Navajo Nation as the nation's largest tribal reservation shifted its model from a council to a nation with three branches of government.
While his term ended in 1995, Zah continued working for several decades to defend the interests of Native American people and was a fervent advocate for education in the Navajo Nation.
After earning a bachelor's degree in education from Arizona State University in 1963, where he was one of the few Indigenous students on campus, he returned to the Navajo Nation and taught adults who sought to learn carpentry skills. Zah later co-founded and became executive director of DNA-People's Legal Services, a nonprofit program for the Navajo, Hopi and Apache people.
Decades later after leaving his post as Navajo Nation president, Zah served as special advisor to the president of Arizona State University on American Indian Affairs. He traveled to tribal communities to talk to families about college and built partnerships with tribal groups.
His guidance over more than a decade helped the school double its Native American student population, according to ASU.
"I am saddened by the passing of Peterson Zah, a groundbreaking and courageous leader who shared his knowledge, passion for education and service, and generosity of spirit to make Arizona State University, Arizona and Indian Country better," Arizona State University President Michael M. Crow said in a statement.
"He set the standard for ASU's commitment to American Indian students and tribal communities, and he will be deeply missed. Our condolences to the Zah family and the Navajo Nation," Crow added.
Zah led efforts to include tribes in the Clean Water Act, the Clean Air Act, and for the amendment of the American Indian Religious Freedom Act in 1994.
"Shida'í, Mr. Zah, molded our people to think as a nation, and, despite his age and health, he never quit in his mission to see us become who we ought to," Navajo Nation Council Delegate Carl Roessel Slater said in a statement. "We are stronger because of his leadership, compassion, intelligence, and gift for elevating the ordinary deliberations our society into echoes of our future."