With no cities or courts, the formidable and nomadic Xiongnu kingdom sent princess emissaries to control its frontiers.

he raiders came from the north. They came on horseback, the skilled bowmen shooting powerful arrows with expert precision. They ruined and burned the crops, which the Han Chinese villagers living on China's northern frontiers in about 200 BCE tended to with great attention. The Han Chinese called the invaders "Xiongnu", which meant "fierce slave", a pejorative term aimed to emphasise the barbarians' "inferiority".

In reality, however, the Xiongnu outperformed their Chinese neighbours in military expertise and political organisation. Comprised of different ethnic tribes, the Xiongnu were the world's first nomadic empire, well-organised and formidable enough to cause so much trouble to the Han Chinese that the latter eventually resolved to build the Great Wall of China. More interestingly, behind the fierce bowmen, it was the powerful Xiongnu women who helped hold the empire together.

Piecing together the Xiongnu's curious history has been a challenge because despite their high organisation and military prowess, the nation never developed a written language. "So the majority of facts we know about Xiongnu come from their graveyards and their enemies," said Christina Warinner, a group leader in the Department of Archaeogenetics at the Max Planck Institute.

And the graveyards tell an interesting story, as a recent study has proven that a surprisingly high number of elite Xiongnu burials hold female remains.

Archaeologists excavating Xiongnu burial sites across Mongolia have long posited that remains in some of the richest and most elaborate graves were female. However, it was only when genetic sequencing technologies finally came of age a few years ago that Warinner's Max Planck team was able to confirm the female gender of several elite burials with absolute certainty, publishing their study findings in the journal Science in April 2023.

"Our genetic findings prove that the elite princesses played important roles in the Xiongnu society, politically and economically," said Jamsranjav Bayarsaikhan, who heads the Research Centre at the National Museum of Mongolia in Ulaanbaatar and is a project coordinator at the Max Planck Institute for Geoanthropology in Germany.

These findings have changed scientists' perspective on how Xiongnu expanded their territory and held their nomadic empire together, and the important role their women played in politics and economy.

We may think of empires as stationary entities that build cities, palaces and courts to maintain their rule, but some nomadic kingdoms were incredibly robust. Predating the famed Genghis Khan empire by about 1,000 years, the Xiongnu empire lasted from the 2nd Century BCE to the late 1st Century CE and occupied the territory of modern-day Mongolia with its northern borders stretching all the way to Lake Baikal in today's Russia.

Besides being skilled warriors, Xiongnu were also avid purveyors of luxury goods, which they acquired from across Eurasia through the trading routes of the ancient Silk Road – including Chinese silks, Roman glass and Egyptian beads. The elite Xiongnu women held important positions in society and were involved in politics. In a way, Xiongnu women were the virtual glue – or perhaps the silk ties – that held together the roaming kingdom, which didn't have permanent cities or brick-and-mortar fixtures to assert its presence.

"Xiongnu women held great imperial power along the frontier, often holding exclusive noble ranks, maintaining Xiongnu traditions, and engaging in both steppe power politics and the Silk Road networks," said Bryan Miller, assistant professor of archaeology at the University of Michigan, US, also on the Max Planck team. "They were highly respected."

"These burials of women often have grave goods in them that are symbols of power and leadership," added Warinner.

At the elite cemetery of Takhiltyn Khotgor, located in the Mankhan district of Khovd province in western Mongolia, the researchers found monumental tombs clearly built to honour the women. Resting in elaborate coffins decorated with Xiongnu's imperial symbols of golden sun and moon, each female was surrounded by a host of commoner males placed in simple graves. One tomb contained six horses and a chariot.