Sanders' visit may remind some of a sensitive subject for Warren, still criticized after her October release of a DNA test meant to bolster her claim to Native American heritage. That was supposed to rebut President Donald Trump's mocking of the Massachusetts senator as "Pocahontas," but only intensified it.
Last month, Warren offered a public apology to Native Americans, trying to show that the issue won't be a political drag on her White House campaign, which polls show on the rise lately. The Comanches, who are holding their 28th annual Nation Fair Powwow, are a Plains Indian tribe of about 17,000 enrolled members, with headquarters just north of Lawton, in southwest Oklahoma. Powwows are important social events for many tribes, featuring traditional dance, songs, food, regalia and other customs, and Sunday's was held at the tribe's headquarters in the foothills of the Wichita Mountains.
Sanders, a Vermont senator, entered the powwow grounds in a procession of tribal leaders, led by a group of Comanche women dancers in traditional dress. He was presented with a Comanche Nation Blanket.
"What you understand, and what you have taught us — and it is a lesson that must be learned now or the entire planet will be in danger — you have taught us that, as human beings, we are part of nature and we cannot destroy nature and survive," Sanders said, adding that Native Americans have "enriched the American people. You have educated the American people."
"I know and you know that, for too many years, the needs of the American Indian have been ignored, treaties have been broken and lie after lie has been told to you," Sanders said. The value of Sanders' visit was more symbolic than practical since the Comanche Nation is not particularly large, said University of Oklahoma political science professor Keith Gaddie.
"There's no reason, in order to win the state, that you'd have to go down to that event," Gaddie said. Indeed, Comanche Chairman William Nelson, Sr. said that no presidential candidate had visited the Comanche Nation since Teddy Roosevelt came to Oklahoma to hunt wolves while still a White House hopeful.
"It's an honor that an actual candidate for president would visit the Comanche Nation," Nelson said. Sanders won Oklahoma's 2016 Democratic primary over Hillary Clinton. The state votes next year as part of the earlier and expanded "Super Tuesday," which comes on March 3 and includes neighboring Texas.
Warren has made her family's financial struggles — after her father had a heart attack and couldn't work forcing her mother to get a minimum wage job — a central theme of her campaign. She and Sanders are friends who agree on many policy issues, including the "Medicare for All" universal health insurance plan.
Both also have refused to attack one another politically, ducking questions about whether they eventually will have to compete for the Democratic Party's most liberal wing. But a Des Moines Register-CNN-Mediacom poll released Saturday showed Warren outpacing Sanders in Iowa, which launches the 2020 Democratic nominating contest on Feb. 3. She also was running about even with former Vice President Joe Biden, who had been the crowded field's front runner.
As expected, Sanders did not mention Warren on Sunday, instead telling those gathered that, if he's elected president, "Not only will you get a seat at the table, you will be part of the decision making."
Stephanie Landeros, a Comanche Indian from nearby Apache, said she supports Sanders because of his position on issues that are important to her, including civil rights, protecting the environment and programs for the poor.
"He seems to be someone who is concerned about minorities," Landeros said.
Weissert reported from Washington.