On Sunday, tribes from the U.S. and Canada are convening in Jackson to sign a historic treaty to pledge their dedication to protecting the grizzly bear. The signing comes in advance of a proposal by the U.S. Fish and Wildlife Service to delist the Yellowstone grizzly from the Endangered Species List by the end of the year.

Tribes from around the region, including the Cheyenne, Blackfeet and Wyoming’s Northern Arapaho and Eastern Shoshone, all intend to sign the treaty. By signing, they agree to ban grizzly trophy hunting on their reservation and to reintroduce the species on tribal lands if possible.

Chief Stan Grier of Canada’s Piikani Tribe says it’s the first cross border treaty in 150 years, and that it’s the role of the grizzly in Native customs that unites so many tribes.

“The grizzly is fundamental to our ceremonies and spiritual practices. So to do this represents to us an act of cultural genocide,” Grier says.

The signing of the treaty is open to the public and will take place on Sunday afternoon at two at the Jackson Lake Lodge.