Around 36 BCE, Chinese forces from the Han Dynasty fought a group of rebels called Xiongnu at a fortress in what is now Kazakhstan.
During the battle, the Chinese noticed their enemy employed a strange but distinctive formation. One historian at the battle recalled a unit that formed a unique "fish-scale"-style of protection using their shields.
Some modern historians think that "fish scale" was a Roman phalanx.
The "Testudo" (turtle) formation of a Roman phalanx performed by re-enactors. (photo by Neil Carey)
The battle took place in a city that was once known as Liqian, now a part of Gansu province in Northern China. And strangely, people living where the old city once stood are known to have interesting genetic traits unlike people in the rest of the country.
Aqualine noses, green eyes, and fair skin are just a few of the features found among the villagers of Zhelaizhai, where the ancient city once stood.
Some historians believe the people of Zhelaizhai are descended from the Roman Legionaries who fought with the Han Chinese.
Just 17 years before the battle in Kazakhstan, Parthians fighting the Romans at the Battle of Carrhae (in modern-day Turkey) delivered one of Rome's most crushing defeats. They captured 10,000 legionnaires and sent the powerful Roman General Marcus Licinius Crassus packing (parts of him, anyway).
Parthians were known to use captured soldiers as border guards and sent their POWs to the Far East, where escape was all but impossible. That Far East outpost is thought by some to be the ancient area of Liqian.
That's a long walk.
Nowadays, the Gobi Desert border regions are full of ethnically Chinese people whose DNA tested 58% Caucasian.
The theory does have naysayers. Some believe the DNA could be the result of contact from Silk Road trading between Rome and the Far East. Others say Caucasian Huns and warriors with other racial backgrounds fought through this area of Asia at the time.
At least one expert believes there just isn't enough physical evidence to say these Chinese are descended from Roman legionaries.
"For it to be indisputable, one would need to find items such as Roman money or weapons that were typical of Roman legionaries," Maurizio Bettini, an anthropologist from Siena University, told La Repubblica. "Without proof of this kind, the story of the lost legions is just a legend."