A long-running political dispute between two American Indian tribes forced more than a century ago to live together on a Wyoming reservation has spilled into the courtroom, with one accusing the other of violating its sovereignty.

More than 10,000 Northern Arapaho and 4,000 Eastern Shoshone Indians live on the Wind River Reservation, in a rural basin ringed by mountains. The two tribes — historic adversaries made to live side-by-side in the 1860s — for decades maintained separate governments, but have met regularly through a joint council.

Now, after the Arapaho attempted to dissolve the council two years ago, the tribe is suing two Shoshone leaders in federal court in Montana. The suit filed Monday claims Eastern Shoshone leaders unilaterally revived the joint council and approved mineral leases and made hiring decisions without consulting the Northern Arapaho.

The Arapaho also allege officials from the U.S. Bureau of Indian Affairs encouraged the Shoshone to take independent action affecting both tribes, despite the Arapaho's objections.

"One tribe can't run programs for another without its consent," Northern Arapaho Business Council Chairman Dean Goggles said in a written statement.

The lawsuit before U.S. Judge Susan Watters in Billings seeks to bar the defendants from spending money on programs affecting the Arapaho without the tribe's input. It also seeks to cancel or alter contracts between the Shoshone and the Bureau of Indian Affairs. Further details on those contracts were not immediately available.

Eastern Shoshone Chairman Darwin St. Clair and Vice Chairman Clint Wagon, defendants in the lawsuit, were not immediately available for comment Tuesday, according to the tribal office.

Also named as defendants were five representatives of the Bureau of Indian Affairs, including the agency's director, Michael Black and Rocky Mountain Region Director Darryl LaCounte.

Bureau spokeswoman Nedra Darling said the agency does not comment about matters under litigation.

Before being placed on the Wind River Reservation, near the town of Lander, the Eastern Shoshone and Northern Arapaho tribes ranged the western Great Plains. They periodically warred with each other and with other tribes, a consequence in part of the pressures on their hunting grounds brought by the United States' western expansion.

In 1863, the Eastern Shoshone signed a treaty establishing the 69,000-square-mile Shoshone Reservation, later renamed Wind River, according to the tribe. That land base was reduced to 4,300 square miles by a second treaty signed five years later, the same year the Northern Arapaho tribe was placed on the reservation by U.S. officials.