Archaeological excavations revealed twenty-five 13th century male soldiers buried in a pit near a Crusader castle near Sidon, south Lebanon.

Studying the DNA of those uncovered, researchers from the UK, Lebanon and Belgium were able to identify nine Crusaders’ ancestry, revealing that three were western Europeans, four were genetically very similar to modern-day Lebanese people, and two individuals had mixed genetic ancestry between European and eastern background.

The Crusaders battled in the 1200s as part of a diverse army of the crusaders’ kingdom of Jerusalem over two centuries consisting of western and Eastern Europeans.

First author of the Wellcome Sanger Institute, Marc Haber, explained that one of the two men must have had a Lebanese parent while the other hailed from somewhere in Europe.

“The other one is more interesting I think because one of the parents is someone who looks [genetically similar to] Bedouin or Saudi [people], and the second parent is northern Spanish or Basque. The first Crusades predate [the remains] by about 100 years, so there is plenty of time for them to be second or third generation,” he stated.

“We suggest they were fighting with them, not against them, because we know from history that the Arab armies that were fighting against the Crusaders came from places like Syria, Turkey, Iraq or Egypt, where the people genetically are different from the near-eastern individuals we found in this pit,” Haber added.

"We know that Richard the Lionheart went to fight in the Crusades, but we don't know much about the ordinary soldiers who lived and died there, and these ancient samples give us insights into that," a genetics researcher at the Wellcome Sanger Institute and senior author, Chris Tyler-Smith, said in The American Journal of Human Genetics article.

"Our findings give us an unprecedented view of the ancestry of the people who fought in the Crusader army. And it wasn't just Europeans. We see this exceptional genetic diversity in the Near East during medieval times, with Europeans, Near Easterners, and mixed individuals fighting in the Crusades and living and dying side by side,” Haber highlighted.

Researchers pointed out that although human migration modifies the genetic makeup of a region, those Crusaders’ impact was short-lived because the genetic traces found in the people living in Lebanon today are insignificant.

"They made big efforts to expel them, and succeeded after a couple of hundred years," Tyler-Smith explained.

“Those were the regular normal people who are also mixing together, and their sons were joining the fight later on,” Haber said.

The study used existing genetic data from modern-day people and a wider range of ancient individuals, as well as newly extracted DNA from local Roman remains, to make comparisons.

"If you look at the genetics of people who lived during the Roman period and the genetics of people who are living there today, you would think that there was just this continuity. You would think that nothing happened between the Roman period and today, and you would miss that for a certain period of time the population of Lebanon included Europeans and people with mixed ancestry," Haber noted.

The study stated that while the genetics of modern Lebanese Christians show little difference to medieval people from the region, those of modern Lebanese Muslims have some difference as they mix more with other populations including Turks after the Crusades.

“They do use local Christians in their armies. This really does kill it stone dead,” Prof Jonathan Phillips, from Royal Holloway, University of London, affirmed that crusaders actually engaged with the local population.

"Our findings suggest that it's worthwhile looking at ancient DNA even from periods when it seems like not that much was going on genetically. Our history may be full of these transient pulses of genetic mixing that disappear without a trace," the authors pointed out as studying the DNA might not have traces of the people attacking and residing in the country.

"There has been a lot of long-term interest in the genetics of this region, because it has this very strategic position, a lot of history, and a lot of migrations. But previous research has focused mainly on present-day populations, partly because recovering ancient DNA from warm climates is so difficult. Our success shows that studying samples in a similar condition is now possible because of advances in DNA extraction and sequencing technology," Haber appeased over the possibility of the study.

"Historical records are often very fragmentary and potentially very biased; but genetics gives us a complementary approach that can confirm some of the things that we read about in history and tell us about things that are not recorded in the historical records that we have. And as this approach is adopted by historians and archaeologists as a part of their field, I think it will only become more and more enriching,” Tyler-Smith stressed.