Sen. Elizabeth Warren (D-MA) surprised attendees at the National Congress of American Indians in Boston on Wednesday, using the appearance to give a speech denouncing President Donald Trump’s use of the nickname “Pocahontas” to belittle her claims of Native American heritage.

“I’ve noticed that every time my name comes up, President Trump likes to talk about Pocahontas. So I figured, let’s talk about Pocahontas,” Warren told the audience. She went on to detail the real story of Pocahontas and how the narrative has been taken away from the Native American community and twisted by more powerful people.

“Our country’s disrespect of Native people didn’t start with President Trump. It started long before President Washington ever took office,” she said.

Warren also used the appearance to directly address the sensitive issue surround her claim to Native American ancestry, which has drawn continuous criticism from both the right and left.

“I get why some people think there’s hay to be made here. You won’t find my family members on any rolls, and I’m not enrolled in a tribe,” Warren said. “And I want to make something clear. I respect that distinction. I understand that tribal membership is determined by tribes — and only by tribes. I never used my family tree to get a break or get ahead. I never used it to advance my career.”

The issue of Warren’s native ancestry began with her 2012 Senate campaign, during which opponents criticized her for claiming Cherokee heritage to advance herself through affirmative action. There is currently no evidence that Warren has ever been the beneficiary of any ethnicity or race-based preference in admissions or hiring. There is also, however, no genealogical documentation for the partial Cherokee ancestry Warren has claimed in the past.

In spite of this, Warren told the story of her family history Wednesday, saying, “I want to make something else clear too: My parents were real people.” Her mother, part Native American, and her father, a white man, fell head over heels in love with each other and eloped against their families wishes.

She used the story of her family’s struggle to make clear she is now fully committed to uplifting the voices of Native communities, but didn’t specify exactly how she intends to do so.

Warren has been criticized for not doing enough for the community she claims she is a part of. But Trump’s repeated use of the slur “Pocahontas” has allowed Warren to become an advocate for Native Americans.

“Our stories are deeply woven into the fabric of who we are. The stories of immigrants and slaves, of explorers and refugees, have shaped and reshaped our country right up to the present day,” said Warren. “For far too long, your story has been pushed aside, to be trotted out only in cartoons and commercials.”

“So I’m here today to make a promise: Every time someone brings up my family’s story, I’m going to use it to lift up the story of your families and your communities.”