Morton County Sheriffs Department(NEW YORK) — For the Standing Rock Sioux Tribe, the controversial Dakota Access Pipeline perpetuates a long history of broken promises made by the U.S. government.

“We live with so many broken promises, there’s no reason for it,” Dave Archambault II, the chairman of the tribe, told ABC News.

“We understand what lands we own, and what lands were illegally taken from us,” he added.

The nearly 1,200-mile-long, $3.7-billion Dakota Access pipeline plans to cross the Missouri River just north of the Standing Rock Reservation, prompting concerns for the safety of the tribe’s drinking water and preservation of its sacred sites.

For months, the Standing Rock Sioux and their supporters have camped out along the banks of the Missouri River in an effort to stop the controversial project. Hundreds of protesters, or water protectors, as they prefer to be called, have been arrested since the protests began, many charged with criminal trespassing. But the protesters say they aren’t trespassing; in fact, they say they are the victims, citing the broken treaties their ancestors made with the U.S. government.

The proposed route passes through land that was once set aside for the Sioux in the 1851 Treaty of Fort Laramie. That historic agreement ensured the Sioux could retain portions of five states, but ceded all of their land east of the Missouri River to the U.S. government in exchange for money, agricultural aid and strict rules about any access to Sioux territory by outsiders. However, the agreement was short-lived.

“Before the ink was dry, westerners were coming in,” Archambault said.

The U.S. government did little to stop white settlers from infringing, according to the State Historical Society of North Dakota.

Things only got worse for the Sioux after gold was discovered at the headwaters of the Missouri River in 1861, prompting a flood of settlers. The tribes repeatedly objected to the intrusions and demanded government recognition of the 1851 Fort Laramie Treaty, but their complaints fell on deaf ears.

By 1868, the U.S. government and representatives of various Sioux tribes convened once again at Fort Laramie. The resulting treaty established a much smaller territory known as the Great Sioux Reservation, but under Article 12 no further land loss could occur unless approved by three-fourths of adult Sioux males.

Nevertheless, after gold was discovered in the sacred Black Hills of South Dakota deep in Sioux territory, Congress passed the Act of 1877 which ceded the Black Hills to the United States without tribal approval in one of the most controversial land grabs in U.S. history.

More than a century later in 1980, the Sioux took the Black Hills case to the Supreme Court and won a decision that rewarded the tribe with more than $100 million. To this day, the Sioux have refused to accept the funds, hoping instead to get back the sacred land itself.

After seizing the Black Hills, Congress moved to further reduce the Great Sioux Reservation in acts passed in 1887 and 1889, dividing it into fragments of its original 1868 version.

Since then, the Standing Rock Reservation’s borders have essentially remained the same, though the tribe claims it lost thousands of acres of its best lands to flooding after the government erected several dams along the Missouri River without consulting the tribe in the mid-20th century.

It’s a dark history that weighs heavily on the Standing Rock Sioux and their sympathizers. Just last week, the Army Corp of Engineers, the government agency responsible for determining whether to issue the final easement necessary for the pipeline to cross the Missouri River, announced that “additional discussion and analysis are warranted in light of the history of the Great Sioux Nation’s dispossessions of lands,” according to a statement released on Nov. 14.

“It’s like a perpetrator committing a crime on an innocent individual,” Archambault told ABC News. “If you do it once, you should be stopped; if you do it again, you should be stopped; if you’re not, you become a serial perpetrator time and time and time again, and today we are saying, ‘No, don’t put this pipeline here, enough is enough,’” he said.

Copyright © 2016, ABC Radio. All rights reserved.