OKLAHOMA CITY (Reuters) - The nation’s second-largest Indian tribe formally booted from membership thousands of descendants of black slaves who were brought to Oklahoma more than 170 years ago by Native American owners.

The Cherokee nation voted after the Civil War to admit the slave descendants to the tribe.

But on Monday, the Cherokee nation Supreme Court ruled that a 2007 tribal decision to kick the so-called “Freedmen” out of the tribe was proper.

The controversy stems from a footnote in the brutal history of U.S. treatment of Native Americans. When many Indians were forced to move to what later became Oklahoma from the eastern U.S. in 1838, some who had owned plantations in the South brought along their slaves.

Some 4,000 Indians died during the forced march, which became known as the “Trail of Tears.”

“And our ancestors carried the baggage,” said Marilyn Vann, the Freedman leader who is a plaintiff in the legal battle.

Officially, there are about 2,800 Freedmen, but another 3,500 have tribal membership applications pending, and there could be as many as 25,000 eligible to enter the tribe, according to Vann.

The tribal court decision was announced one day before absentee ballots were to be mailed in the election of the Cherokee Principal Chief.

“This is racism and apartheid in the 21st Century,” said Vann, an engineer who lives in Oklahoma City.

Spokesmen for the tribe did not respond when asked to comment.

The move to exclude the Freedmen has rankled some African American members of Congress, which has jurisdiction over all Native American tribes in the country.

A lawsuit challenging the Freedman’s removal from the tribe has been pending in federal court in Washington, for about six years.

As a sovereign nation, Cherokee Nation officials maintain that the tribe has the right to amend its constitutional membership requirements.

Removal from the membership rolls means the Freedmen will no longer be eligible for free health care and other benefits such as education concessions.