Hopi and other tribal leaders say the commercialization of cultural heritage violates tribal laws. When human remains and sacred objects wind up on the auction block, they say it’s often the result of looting and illegal trafficking.

“These items are part of living cultures,” said Eldred Lesansee, a cultural sovereignty fellow at the Association on American Indian Affairs, a nonprofit that advocates for tribes. “Indigenous peoples are still here. We still practice on a daily basis our culture, our languages and our traditions. These are simply just a part of us as our identity and that’s where we draw our strength.”

The association is calling on collectors and auction houses to work with tribes to help them find a way to bring their artifacts and ceremonial items back home.