Indigenous leaders from the U.S. and Canada gathered in Calgary on Wednesday to sign a declaration of opposition against the proposed Keystone XL pipeline.

The leaders say their coalition represents thousands of First Nations people in opposition to the TransCanada project and wanted to be in the company's hometown to express their concern.

"We've been waiting for this — for a long time — for our nations to come together and it's an honour to witness that," said Neskonlith Chief Judy Wilson from B.C. 

The ceremony included leaders of the Blackfoot Confederacy in Canada, which includes Indigenous people in British Columbia, Alberta and Saskatchewan, as well as the Great Sioux Nation in the U.S.

Opposition to expansion of oilsands

The 16-page declaration highlights their treaty rights and their opposition to the proposed $8-billion pipeline, which would move Canadian crude south to Nebraska, where the pipeline would connect with an existing Keystone pipeline network that would take the oil to Texas Gulf Coast refineries.

The document also included opposition to the expansion of Alberta's oilsands.

"We don't oppose development and we don't oppose other exploration opportunities for various tribes at their discretion," said Piikani Nation Chief Stan Grier of the Blackfoot Confederacy.

"But rather what we are saying here, with this declaration… is there needs to free, prior and informed consent when it relates to Indian country."

Casey Camp-Horine, who travelled from Oklahoma to take part in the ceremony at the Glenbow Musuem, is an elder and council woman with the Ponca Tribe. 

"I'm amazed and thrilled that this day has come," she said. 

"It is our turn to use the voices that the colonizers understand to say our mother the earth has withstood all that she should ever withstand on our behalf."

TransCanada 

TransCanada, which has both a Native American Relations Policy and an Aboriginal Relations Policy, maintains the pipeline will be environmentally safe and will create jobs and boost the economy.

"We understand and respect that there are some who might have different views about this project," spokesperson Jacquelynn Benson said.

"TransCanada is always interested in the views of our stakeholders along the right of way."

President Barack Obama rejected the project in 2015, but the Trump administration overturned that decision this year.

The project still faces hurdles.

A coalition of environmental groups has challenged the federal permit in court, saying more environmental study is needed.

Nebraska regulators also haven't decided whether to approve the proposed route through that state.

The coalition plans to use Wednesday's document to draw attention to their cause — possibly sending it to the United Nations — while they also consider other opposition, including protest camps along the pipeline route, Camp-Horinek said.

​TransCanada recently said it was reassessing whether oil producers in North Dakota and Montana are still interested in shipping crude through its long-delayed pipeline now that they have other new options to ship their product, including the Dakota Access pipeline.

With files from the Associated Press