When we think of the plague (also known by its equally hardcore name, the Black Death), we think of it wiping out a huge chunk of Europe in the 14th century, seemingly out of nowhere. But according to new research published in Nature, we’re just realizing that the disease may have been around for way longer than that. And it may have been just as deadly back then, too.

Scientists studying ancient cemeteries near Siberia’s Lake Baikal just found DNA from Yersinia pestis, the bacterium that causes plague, in the teeth of hunter-gatherers who lived roughly 5,500 years ago. That makes it the oldest known evidence of plague ever discovered, pushing back our understanding of its arrival by around 200 years.

Now, researchers are rethinking everything they knew about how the plague evolved. It was previously believed that early strains were mild and only became dangerous after humans settled in farming communities and cities, where gross rats, fleas, and densely packed people supercharged epidemics. But this newly discovered set of plague victims wasn’t farmers or city dwellers. There were small groups of nomadic hunter-gatherers and desolate regions of Siberia.

The Black Death May Be Much Older Than Scientists Ever Realized

Plague DNA was found in 18 of the 46 people tested, which is comparable to what scientists have found in the remains of people from the 14^th century’s bigger, more famous appearance of the Black Death. A lot of the victims were children, and a lot of them were members of the same family. All told, researchers found evidence of at least two separate outbreaks happening centuries apart.

There is some debate as to how it was able to spread so quickly, whether it was carried around by rodents or if it was spread through the air via sneezes and coughs, but either way, what this discovery makes abundantly clear is that the plague had been around for much longer than once thought, and it was always exactly as deadly as we’ve known it to be.

The discovery also raises troubling questions, such as: Is the next pandemic virus already out there, waiting for the right conditions to spread through an increasingly interconnected global populace? Given our recent history, unsettling thoughts like that were not as far-fetched as they once were.