Stories of Viking "shield-maidens" are well known, but how often did women actually fight? The answer, experts told Live Science, depends on how one reads a thin and contested record of texts and graves. The Viking Age, roughly A.D. 793 to 1066, left few writings in the Vikings' own runic system. Much of what survives was written by outsiders or later Norse descendants. In the 12th century, the Danish historian Saxo Grammaticus wrote in the "Gesta Danorum" that "there were once women in Denmark who dressed themselves to look like men and spent almost every minute cultivating [combat] skills," putting "toughness before allure" and aiming "at conflicts instead of kisses." A medieval Irish text, the "Cogadh Gaedhel re Gallaibh," refers to a "Red Lady" leading a Viking fleet in a raid on Belfast in the 10th century.

Those accounts do not settle the question. Neil Price, an archaeology professor at Uppsala University who has written extensively about the Vikings, told Live Science the Irish passage is of debatable accuracy. He suspects Viking women did fight, but not frequently, and that "female warriors were probably a very small minority." Thomas Kristian Heebøll-Holm, a history professor at the University of Southern Denmark, said Saxo is not a reliable source. He writes about female warriors "only in the parts of his work concerned [with] the legendary past of Denmark," and those passages are "not accurate, but moral and fictitious," sometimes drawing on stories of the Amazons.

Archaeology is also hard to read. Researchers know of about 30 Viking Age female burials containing weapons, including three with swords in Scandinavia. Still more women's graves have spears, axes, or knives that could have been weapons, or tools for hunting and farm work. "The first concern is that the weapons were really used by the deceased and were not merely included as signs of special status or social rank acquired through inheritance," said Deborah Shepherd, an independent researcher with a doctorate in archaeology. Graves are often poorly preserved. She said there were likely "some few female warriors, but they were probably only found in the highest ranking families, and their warrior career was probably short-lived." They "wouldn't have fought in the great armies of later centuries but possibly did fight in pre-Christian skirmishes." The Vikings began converting to Christianity between the ninth and 12th centuries.

There is at least one known case of a Viking woman with what may be combat-related injuries. A woman found in Solør, Norway, had a head injury consistent with a sword strike. She was 18 or 19 when she died, was buried with weapons, and lived around the year 900. Ole Kastholm, a curator and senior researcher at the Roskilde Museum, also stressed the uncertainty. The verified picture, as the experts described it to Live Science, is not a hidden army of shield-maidens and not a myth with no basis at all. It is a small number of armed burials, a few contested texts, and a cautious conclusion that some women fought, probably rarely.