This July 24, 1997 file photo shows a plastic casting of the skull from the bones known as Kennewick Man, in Richland, Wash. One of the oldest and most complete skeletons found in North America will be given back to American Indian tribes in Washington state for reburial. President Barack Obama signed a bill Monday, Dec. 19, 2016, with a provision requiring the ancient bones known as Kennewick Man be returned to tribes within 90 days. (AP Photo/Elaine Thompson,File)

The Ancient One is going home.

One of the oldest and most complete skeletons found in North America will be given back to American Indian tribes in Washington state for reburial.

President Barack Obama signed a bill Monday with a provision requiring the ancient bones known as Kennewick Man be returned to tribes within 90 days.

Experts estimate the remains found in 1996 on federal land near the Columbia River are at least 8,400 years old. The discovery triggered a lengthy legal fight between tribes and scientists over whether the bones should be buried immediately or studied.

In 2015, new genetic evidence determined the remains were related to modern Native Americans.

The bill transfers the skeleton, which the tribes call the Ancient One, from the U.S. Army Corps of Engineers to the state archaeology department, which will get it to the tribes.

"We will work closely with that state organization to transfer the remains in an expedited fashion," said Amy J. Gaskill, chief of public affairs for the Army Corps in Portland, Oregon.

It was too soon to say exactly where the bones will go, as several Northwest Indian tribes have been involved in the fight. "We don't know where the bones are going yet," Gaskill said.

The Yakama Nation is among the tribes that have pushed to rebury the bones in the manner their people have followed "since time immemorial," the tribe has said.

JoDe Goudy, chairman of the Yakama Tribal Council, noted that it took 20 years for the tribes to successfully fight for return of the bones.

"He will be returned so that he may finally rest," Goudy said after the bill passed Congress on Dec. 10.

U.S. Sen. Patty Murray first introduced the Water Infrastructure Improvements for the Nation Act, and she was joined by senators from Oregon and Idaho. A provision in the bill called for returning Kennewick Man to the tribes of the Columbia River Plateau.

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