Beginning in 1863, the U.S. Army forced the Navajo to relocate from their territory in the Four Corners region—where Utah, Colorado, New Mexico and Arizona meet—to a desolate reservation along the Pecos River in eastern New Mexico. There, they suffered through crop failure, disease and overcrowding, until an 1868 treaty allowed them to return to a portion of their homeland.

A copy of this historic treaty, long believed missing, was recently restored to the Navajo Nation, as Evan Nicole Brown reports for Atlas Obscura. It is one of three copies known to exist; one is in the collection of the National Archives, and another is thought to have been buried with Barboncito, a Navajo leader who signed the agreement. The third copy belonged to Col. Samuel F. Tappan, a member of the Indian Peace Commission who helped draft the document. In the 1970s, Tappan’s descendants found the treaty in the attic of his home, but “didn’t know people thought it was missing,” Clare “Kitty” Weaver, Tappan’s great-grandniece, tells Cindy Yurth of the Navajo Times.

Weaver became aware of the document’s significance to the Navajo tribe last year, when she attended an event marking the 150th anniversary of the treaty’s signing. She brought her copy to be displayed, and it attracted the attention of a Navajo woman whose name Weaver never learned. But they grasped hands, hugged, “and then the tears started,” Weaver recalled during a press conference in May, according to the Navajo Times. “That was the significant moment when the treaty became not only a historical document. It became a living being.”

At the anniversary event, tribal officials asked Weaver to return her copy as a donation. “[M]y heart knew right away that it should go to the Navajos,” Weaver tells Felicia Fonseca of the Associated Press, though she adds that she did not turn over the document immediately because she wanted to ensure that “the protocols were in place for housing the treaty.”

Following approval by a Navajo legislative committee, the so-called “Tappan copy” was donated to the Navajo Nation on May 29. It will be on view at the Navajo Nation Museum until today and then will travel to Navajo schools and communities. Per Weaver’s stipulations, the treaty must be kept in a climate-controlled environment, protected by an alarm or live security and can only be displayed for a maximum of six months over a ten-year period.

Manuelito Wheeler, the museum’s director, tells Yurth that the Navajo Nation may now be the first tribe to possess an original copy of its treaty with the government. “I’ve asked around, even asked the National Archives, and I can’t find a single other tribe that has their treaty,” he says.

The treaty was signed during a painful chapter of Navajo history. In the 19th century, the Navajo people came into conflict with settlers who were pushing onto their traditional lands, and U.S. military leaders began formulating plans to send the tribe away from the contested area. The U.S. Army launched a scorched-earth campaign, destroying Navajo crops and livestock. More than 10,000 men, women and children were then forced to walk about 400 miles to the Bosque Redondo reservation in New Mexico. The Long Walk, as this forced migration became known, proved deadly—some 200 Navajos died of cold and starvation along the way.

Conditions at Bosque Redondo, where the Navajo were imprisoned alongside 500 members of the Mescalero Apache tribe, were similarly abysmal. The water in the area made the prisoners ill, and they subsisted on meager Army rations after crops were lost to infestations. Winters were frigid, but the Navajo and Mescalero Apache did not have enough wood for fire. “The bringing of us here has caused a great decrease in our numbers,” Barboncito once said of Bosque Redondo, according to Fonseca of the AP.

On June 1, 1868, the treaty, known as Naal Tsoos Saní (“Old Paper”) to the Navajo, was signed. It formally outlined the borders of the Navajo Nation (which was, however, smaller than their traditional territories) and ensured a government-provided education for children, which often resulted in Navajo youth being sent to schools that forced cultural assimilation. Crucially, the agreement allowed the Navajo to return to a portion of their traditional land, marking the end of their imprisonment in New Mexico and making them the only Native American nation to reclaim their ancestral land through a treaty. Having a copy of this historic document in the tribe’s museum will “magnify the resilience of our Navajo people,” says Navajo Nation President Jonathan Nez, per Fonseca.

“We were never ready to be taken off this planet,” Nez adds. “Our people stayed strong.”