In 1999, a farmer stumbled upon an Iron Age grave on Bryher, a small island southwest of England. Inside was a remarkably rich burial, complete with objects like a copper alloy brooch and spiral ring, according to the Art Newspaper’s Maev Kennedy.

Two of the items were especially intriguing: a sword and a mirror. During the period, swords were usually buried alongside men, while mirrors were buried alongside women. So who was the mysterious individual who was buried with both?

“That combination of the two is what threw everyone in archaeology when it was first discovered,” Sarah Stark, a human skeletal biologist at Historic England, tells the Washington Post’s Victoria Bisset.

Now, researchers say they have the answer to the mystery that stumped experts for more than 20 years: The grave belongs to a woman warrior who played a leading role in warfare, according to a study published yesterday in the Journal of Archaeological Science: Reports.

Scientists came to this conclusion by analyzing tooth enamel, which has proteins that vary based on sex. While previous attempts at DNA analysis failed due to the poor condition of the recovered remains—tiny pieces of bone and teeth weighing around 150 grams—enamel is one of the body’s most durable substances, allowing researchers to calculate with 96 percent probability that the warrior was a woman.

“Given the degraded state of the bones, it’s remarkable to get such a strong result. It makes you wonder what could be discovered by re-visiting other badly degraded burials,” says Glendon Parker, an environmental toxicologist at the University of California, Davis, and co-author of the study, in a statement from Historic England.

Enamel analysis has already helped scientists in similar cases, including the recent discovery that Spain’s so-called “Ivory Man” was actually a woman. Stark, who is also a co-author of the study, is interested in analyzing additional burials similar to the one on Bryher. “We might start to uncover more of these hidden female warriors,” she tells the Washington Post.

Discovering that the grave belonged to a woman offers new insights into life in Iron Age Britain. At the time, violence between communities was common. Even mirrors, used to signal or coordinate attacks, could be part of warfare, according to Historic England. They were also used for ritualistic purposes, such as communicating with the supernatural world to ensure victory in an upcoming battle.

“Although we can never know completely about the symbolism of objects found in graves, the combination of a sword and a mirror suggests this woman had high status within her community and may have played a commanding role in local warfare, organizing or leading raids on rival groups,” says Stark in Historic England’s statement. “This could suggest that female involvement in raiding and other types of violence was more common in Iron Age society than we’ve previously thought.”

Kate Hales, a curator at the Isles of Scilly Museum, where the mirror and sword are housed, says the new findings help tell a new story about the items.

“Visitors have been captivated by the mystery that surrounds them,” she tells BBC News’ Brodie Owen. “It’s fascinating to know they were buried with a young woman and we look forward to reinterpreting her story, wondering about the kind of life she led, thousands of years ago on our now tranquil islands.”