What prompted the change?

The labels were quietly added in October, after three years of protests from Decolonize This Place, a group urging institutions to acknowledge how marginalized people were represented. The museum consulted with outside experts but not the protest group.

Amin Husain, a visual artist and member of Decolonize This Place, said the labels work on this diorama “because it honors the fact that that was there to begin with, so it references the harm that has been perpetuated over the years. And then it says, ‘We’re going to tell you how that was wrong.’”

The group has said that more needs to be done. It has asked the museum to re-evaluate other exhibits and to move a statue of Theodore Roosevelt outside the building.

“That has a Native figure and an African figure subjugated to a Roosevelt president, on a horse,” Mr. Husain said. “Put it in the museum itself, and then label it.”

Natasha Singh, 34, another visual artist and member of Decolonize This Place, said she wanted to see “complete systematic changes of the museum.”

What else in town should be changed?

A lot, Ms. Singh and Mr. Husain said. They are not alone.

When city officials discovered that there were only five statues depicting real women in public spaces, they rushed to plan at least five more.

Last year, focus turned to a statue of a 19th-century surgeon who conducted experimental operations on female slaves. It was moved from Central Park to Green-Wood Cemetery in Brooklyn, where the surgeon was buried.