Black Death devastated European populations in the 14th century but scientists have now found the bacteria that caused it has been around for thousands of years.
Scientists now believe that farmers that lived 4,500 years ago may have also been killed by the 'Black Death'.
Yersinia pestis, the bacteria that causes plague, has been found in the remains of a 20-year-old Stone Age woman who died 4,900 years ago in southern Sweden.
This is the oldest trace of the deadly bacteria ever found and scientists say it could rewrite the history on the decline of Neolithic Europeans.
They say the dawn of the Bronze Age and trading of excess goods may have allowed the plague to spread to different regions and into Europe.
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This image shows the remains of a 20-year old woman from around 4,900 ago. She was likely killed by the first plague pandemic. She was one of the victims of a plague pandemic that likely lead to the decline of the Neolithic societies in Europe, scientists claim
Previously it was believed invaders from Asia brought plague with them but the new findings suggest a breakout occurred far before these colonists arrived.
A team of French, Swedish and Danish researchers identified a new strain of Yersinia pestis, the bacteria that causes plague.
Senior author Associate Professor Simon Rasmussen, at the Technical University of Denmark and the University of Copenhagen, explained: 'Plague is maybe one of the deadliest bacteria that has ever existed for humans.
'And if you think of the word 'plague,' it can mean this infection by Y. pestis, but because of the trauma plague has caused in our history, it's also come to refer more generally to any epidemic.
'The kind of analyses we do here let us go back through time and look at how this pathogen that's had such a huge effect on us evolved.'
The evolution of the plague was mapped through genetic data from ancient humans, and sequencing modern plague strains.
Genes that make the pneumonic plague deadly were found in the Swedish remains.
Traces of it were also found in the remains of another person at the site and it is believed the woman did die from the disease.
By comparing it to other strains, the researchers were able to determine that it's also the most basal, meaning that it's the closest strain we have to the genetic origin of Y. pestis.
It likely diverged from other strains around 5,700 years ago and the plague that was common in the Bronze Age and the plague that is the ancestor of the strains in existence today diverged 5,300 and 5,100 years ago, respectively.
This suggests that there were multiple strains of plague in existence at the end of the Neolithic period, according to the researchers.
Professor Rasmussen added the finding offers a new theory about how plague spreads.
Massive human migrations from the Eurasian steppe down into Europe are known to have occurred around 5,000 years ago.
But how these cultures were able to displace the Neolithic farming culture present in Europe at the time is still debated.
Previous researchers suggested the invaders brought the plague with them, wiping out the large settlements