On December 29, 1835, the Cherokee Nation signed the Treaty of New Echota. Like many treaties the U.S. government signed with Native American tribes, this one benefited the United States at the expense of the Native nation. The Cherokee were forced to relinquish their ancestral lands. During their relocation to Oklahoma, on what became known as the Trail of Tears, a quarter of their population perished. Most of the treaty’s promises went unfulfilled.

One provision in the treaty stipulated that the Cherokee were “entitled to a delegate in the House of Representatives of the United States.” Nearly 200 years later, the Cherokee Nation has named their delegate: Kimberly Teehee, a former policy adviser to President Barack Obama and a longtime leader within the Cherokee Nation. Now the government has to honor this centuries-old promise. In a new documentary, The Atlantic follows Teehee on her quest to give her nation a voice in Congress.

“If we don’t get it done now,” Teehee says, “it might not happen.”