The Trust for Public Land (TPL) is a U.S. nonprofit organization that conserves land for people, particularly for watershed protection, scenic beauty, and close-to-home recreation as well as to safeguard the character of communities by preserving historic landmarks and landscapes.
The Tribal Lands Program carries out TPL’s commitment to help Native American tribal governments and communities reacquire and protect our ancient homelands and significant places.
http://www.tpl.org/what-we-do/initiatives/heritage-lands/tribal-and-native-lands.html