This may sound like a news flash from the 19th century, but it happened last month: The president signed a little-noticed bill officially recognizing six Indian tribes and allowing them to request new reservations. Given that reservations are among the poorest, most desperate communities in the U.S., with high rates of crime, alcoholism, suicide and domestic abuse, it’s odd that President Trump would want to establish more of them.

The bill Mr. Trump signed into law grants federal recognition to six Virginia tribes comprising some 4,400 people, who can now ask that public lands be held “in trust” for them, which limits individuals’ economic and private-property rights. It’s hard to think this will do anything but invite bureaucratic intrusion and make tribal members more dependent on public funds.

Although the law will not give the tribes the right to open casinos, businesses on reservations can operate tax-free. That would give them an economic advantage over nearby Virginians who are not of Indian descent; the trouble is that it would also tilt the economy toward products that are highly taxed elsewhere, like cigarettes, liquor, gas and marijuana (which tribes have been free to legalize since 2014). This is hardly a route to success, as the experience of other reservations shows.

Who are these tribes and why has recognizing them taken until 2018? Stephen R. Adkins, chief of the Chickahominy tribe, told the House in 2007 that his group traces its lineage back to Pocahontas and other Native Americans who greeted the first English settlers: “Our connection to Pocahontas and, by extension, to England must come full circle and extend to the Congress of the United States of America. We must feel the same honor and love from leaders of the United States of America as we do from the people from England with whom our last treaty was signed in 1677.”

But the Virginia tribes have offered little proof of their ancestry. This is why the Bureau of Indian Affairs, under Presidents Bush and Obama, declined to grant them formal recognition. The tribes have argued they could not prove this connection in the required way because they had experienced “paper genocide.” They claimed that Virginia passed a law in 1924 requiring that all nonwhites be listed as “colored” on public documents, meaning local Indians could not be effectively distinguished from other racial groups.

In 1997, Virginia’s then- Gov. George Allen signed legislation intended to remedy the situation, and the Virginia General Assembly urged that the tribes be recognized. But the Bureau of Indian Affairs continued to dispute their claims. In 2009 testimony before the U.S. House, Lee Fleming, director of the BIA’s Office of Federal Acknowledgment, said one of the groups had submitted 17 birth certificates issued from 1915-49, all of which included a designation of Indian. “These groups have the opportunity to submit the same types of records that all the other petitioning groups submit,” Mr. Fleming said. So why did they have such difficulty tracing their roots?

Recognition by the BIA, however, is not really the endgame for tribes, since only Congress can give them reservation land and many of the accompanying benefits. That’s why some tribes—including the Mashantucket Pequots of Connecticut in 1983 and the Graton Rancheria of California in 2000—bypassed the BIA and went directly to Congress. The Virginia tribes have long had the support of their state’s congressional delegation, whose members on both sides of the aisle are happy to say they have helped right a historical wrong while at the same time bringing home federal goodies.

Whether it will ultimately help members of these tribes is another question. One dissenting member of the Lumbee tribe of North Carolina, which is fighting for its own federal recognition, told me in 2014: “If we get more checks, we will have more alcohol. It will be detrimental to the Lumbees.” He was convinced it was a terrible idea for the federal government to hold land “in trust” for his people. “We need less government in our lives,” he said.

Mr. Trump used to be skeptical of new tribal designations. In 1993 he appeared before the House Native American Affairs Subcommittee to testify about Indian casinos. In the video, which was widely publicized during the 2016 election, Mr. Trump asked Rep. George Miller (D., Calif.): “Why are you being discriminatory? Why is it that the Indians don’t pay tax, but everybody else does—I do?”

Even if you approve of what effectively amounts to a reparations policy—albeit one that doesn’t seem to help most Indians escape poverty—shouldn’t such set-asides be reserved for people who can actually document their ancestry? As Mr. Trump told Rep. Miller : “If you look at some of the reservations that you’ve approved, you, sir, in your great wisdom have approved, I will tell you right now—they don’t look like Indians to me . . . . And a lot of people are laughing at it. And you’re telling how tough it is, how rough it is to get approved.”

Before the next tribal recognition bill arrives on the president’s desk, someone at the White House might want to watch that video.