An encampment at the protest against the Dakota Access pipeline near the Standing Rock Indian Reservation near Cannon Ball, N.D. (Stephanie Keith/Reuters)

In the Dakota language, the word “oahe” signifies “a place to stand on.”

And that’s what the Standing Rock Sioux and its allies in the environmental and activist movements say they are doing: using Lake Oahe in North Dakota as a place to take a stand by setting up camps and obstructing roads to block the controversial $3.7 billion Dakota Access pipeline.

Their confrontations with police — who have responded with water cannons, pepper spray and rubber bullets — have steered attention to the 1,170-mile-long oil pipeline project and its owner, Energy Transfer Partners. But the real source of Native Americans’ grievance stretches back more than a century, to the original government incursions on their tribal lands. And those earlier disputes over their rights to the land, like the one over the Dakota Access pipeline, pitted the tribes against a persistent force, the Army Corps of Engineers.

The federal government has been taking land from Lakota and Dakota people for 150 years, tribal leaders say, from the seizure of land in the Black Hills of South Dakota after the discovery of gold in the 1870s to the construction of dams in the Missouri River that flooded villages, timberland and farmland in the Dakotas in the 1950s.

Through the ages, the warring tribes of the Northern Plains lived, hunted and fought across a sprawling expanse of land. Many were migratory, moving with the seasons. Each treaty with the U.S. government, most notably the 1851 and 1868 treaties of Fort Laramie, restricted their movement further, although they left them large areas west of the Missouri River and recognized them as sovereign nations.

In freezing temperatures, police used water cannons on protesters just north of the Standing Rock Indian Reservation in North Dakota Nov. 20. In a Facebook post, law enforcement officials said they were involved in an "ongoing riot." (Zoeann Murphy,McKenna Ewen/The Washington Post)

Much of this was contested, leading to Gen. George A. Custer’s ill-fated military campaign to protect miners. Land was later taken to make way for homesteading.

In 1889, Congress passed legislation that created the modern reservation system, pushing the Sioux, also known as Lakota, into smaller areas. And later in the 1900s, a series of dams across the Missouri River rolled back the scope of those reservations, too.

“This government honors international treaties like they are the Holy Grail, but within our own homeland, they find ways to break them,” said Standing Rock Sioux Chairman David Archambault, who, under the treaties and U.S. law, is the head of a domestic sovereign nation.

Lake Oahe illustrates his point. The lake, the site of the current dispute, exists because of a dam project built by the Army Corps of Engineers, the same agency that has been weighing whether and where the Dakota Access pipeline could be built.

Empowered by the Flood Control Act of 1944, the Army Corps erected the Oahe Dam in central South Dakota, forming a reservoir that extends about 250 miles upstream to within a short distance of Bismarck, N.D. In 1962, President John F. Kennedy dedicated the dam, hailing it as a symbol of a free society tapping its natural resources.

But for the Lakota tribes, the dam didn’t exploit natural resources. It buried them.

The project inundated and destroyed the Standing Rock Sioux tribe’s “most fertile bottom lands,” home to medicinal plants, wildlife and timber, said Everett J. Iron Eyes Sr., former water and natural resource director for the Standing Rock Sioux tribe and now a water consultant. In the process, he said, the Army Corps acquired 56,000 acres of land and destroyed 90 percent of the tribe’s timberland.

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The Army Corps simply condemned the land and paid little to no compensation. The Standing Rock Sioux sued and won compensation — $90.5 million in a trust fund from which it can draw only from the interest on the account to spend on social welfare and economic development.

Iron Eyes said that the government also changed the tribe’s water boundaries. Originally, according to the law passed by Congress in 1889, the tribe’s territorial boundary stopped at the low water level mark on the east bank, giving it ownership of the water and river bed. After building the dam, the Army Corps seized strips of land on either side of the river. Those strips are the areas in dispute now, giving the Army Corps a central role in letting Energy Transfer Partners complete the line, or not.

“When they dammed the Missouri River, they did it specifically and purposely so that it would flood the Standing Rock reservation,” said Harry Sachse, a partner at the Washington firm of Sonosky, Chambers, Sachse, Endreson & Perry who has represented other Native American tribes. “So the Standing Rock tribe still feels very abused. The government drowned all of the towns the tribe built along the river.”

Under the Fort Laramie treaties, the Standing Rock Sioux’s northern border was recognized as the Heart River, which winds up to Bismarck, about 25 miles north of the Cannonball River that was declared the northern border by an act of Congress in 1889. The pipeline battles of the past three months have taken place near the Cannonball.

“They violated every treaty ever made with the tribe,” Iron Eyes said.

“It’s important not to lose sight of the greater sovereignty issue,” said Jennifer Baker, a senior associate at the law firm Fredericks Peebles & Morgan who has represented tribes. “That’s what the [Dakota Access pipeline] fight and all the fights against these ticking environmental bombs really boil down to. To overlook that would be to not do justice to such an important cause.”

The Standing Rock Sioux are not alone in harboring old grievances, many involving the Army Corps and its dams, Sachse says.

The Kinzua Dam in Pennsylvania on the Allegheny River, built in the 1960s, forced more than 600 Seneca families to leave their homes and submerged 10,000 acres of ancestral land. Indians say the project, built by the Army Corps, broke a 1794 treaty signed by President George Washington.

The Colville Confederated Tribes sued the government over the Grand Coulee Dam in Washington state, which blocked salmon fishing sites the tribes had used for centuries. The tribes were eventually awarded $52 million and a percentage of the dam’s electricity, which turned out to be worth about $25 million a year, said Sachse, who represented the Colville tribe.

In Minnesota this year, the Prairie Island Indian Community bought 112 acres of agricultural land near St. Paul to secure a future home. On its reservation, about 30 miles southeast of the Twin Cities, the tribe has wrestled with flooding from the Mississippi and Vermillion rivers. The reservation has about 3,100 acres of land held in trust by the U.S. government. Located in the 100-year floodplain, the land is unusable for development.

In addition, increased rail traffic, including trains carrying crude oil, often blocks the only access point to Prairie Island, according to the tribe’s website.

Native American disputes are not just history; they are still alive.

In 1980, the Supreme Court affirmed a Court of Claims ruling and awarded $106 million to the Sioux tribes for the illegal seizure of the Black Hills. “A more ripe and rank case of dishonorable dealings will never, in all probability, be found in our history,” the court said. But the Sioux rejected the money and continue to seek the return of the land.

Will the Dakota Access pipeline take its place in a bitter history? The pipeline would carry as much as 570,000 barrels a day of shale oil from North Dakota’s Bakken field to the pipeline networks in Patoka, Ill. Along the way, it crosses more than 200 waterways, including the Missouri upstream from the Standing Rock Sioux’s facilities for siphoning off drinking water.

Energy Transfer Partners did not advance its cause when its chief executive, Kelcy Warren, said in an interview on PBS that he wished the tribe had consulted with the company earlier. Nor did Julie Fedorchak, the North Dakota Public Service Commission chair, who told NPR that the Standing Rock Sioux failed to take part in the 11-month permit process or in 30 hours of open hearings, and that their efforts to reach chairman Archambault were futile.

Archambault said in an interview with The Washington Post that the tribal council had in fact met with Energy Transfer executives at the tribal headquarters in September 2014 and that the tribal leaders had clearly stated their opposition to the pipeline.

The tribe had passed a resolution in 2012 opposing new pipelines and declared a moratorium on hydraulic fracturing, or“fracking,” within its borders “because we see the destruction done to Mother Earth,” Archambault added. Shale oil produced by fracking in western North Dakota is the main source of crude for the Dakota Access pipeline project.

In mid-November, the tribe posted on its Facebook page a recording of the 2014 meeting, in which Archambault warned pipeline company representatives that the tribe still recognizes the Fort Laramie borders, and therefore the pipeline that the company considered 1,500 feet north of the reservation was, in fact, part of the tribe’s territory.

“So just that you know this is something that the tribe is not supporting,” he said on the recording.

Archambault, in his interview with The Post this year, said Energy Transfer Partners and public officials fundamentally didn’t understand the issue around the pipeline.

“They would consider us a stakeholder, but we’re a nation,” he said. “We would hope and pray they would understand that and consider a more formal government-to-government relationship with the tribe rather than treat us as a stakeholder.”

Energy Transfer Partners, which on Monday announced a merger with Sunoco in an exchange of shares, had once hoped to keep the Dakota Access pipeline out of the limelight. It has argued that this pipeline isn’t unusual. A natural gas pipeline lies along a similar route. And railroads pose similar hazards. This pipeline, the company says, is just one of hundreds of pipelines that carry crude oil, natural gas and refined petroleum products across the country.

The Standing Rock Sioux have raised concerns about a possible pipeline leak in the Missouri River; other pipelines have leaked into rivers over the past five years, including some relatively new ones. Warren, the chief executive, says the pipeline’s foes need not worry about leaks or accidents. The pipeline, he says, is made of extra-thick steel and will run 90 to 115 feet below the bottom of Lake Oahe.

But the Native American opposition to the pipeline project runs much deeper than that.