Nomadic tribes thrived in Greece following the collapse of the Roman Empire.

Analysis of pollen from Greece's Lake Volvi has unexpectedly revealed that nomads flourished in the region for centuries after the turmoil caused by the fall of the Roman Empire.

Adam Izdebski Researchers from Germany's Max Planck Institute for Geoanthropology were studying the lake's sediment cores as part of a larger study. As lake sediment accumulates, changes in the amount of different types of pollen in the sediment layer can record how nearby vegetation has changed over time.

In several other parts of the Mediterranean, the research team found signs of reforestation around 476 AD after the fall of the Western Roman Empire. But in Lake Volvi, starting around 540 AD, the researchers found that there was less tree pollen and more pollen from related plants. Nomadic livestock herders. These nomads returned to the same areas seasonally, so they planted crops such as barley.

“We're at the point where Roman agriculture is almost completely wiped out by disease, climate change, and war, but we can't replant it; in fact, it's going to be deforested very quickly,” Izdebski says.

“Even in the high mountains, the landscape was dominated by pasture animals. This was a complete shift from the way the Romans had cultivated the lowlands for hundreds of years.”

This means early farmers migrated, died, or adopted a nomadic lifestyle, he says.

At the time of this transition, Greece was nominally under the control of the Eastern Roman Empire, or Byzantine Empire. It is known that the area was raided by Bulgar nomads around 540 AD, but it was not known that nomads had lived in the area for centuries.

The only historical information that correlates with the researchers' findings is that a Byzantine emperor was ambushed by Bulgar nomads around 700 AD.

“It seems like there were local communities that didn't want the emperor to exist,” said Izdebski, who presented the findings at the European Geosciences Union conference in Vienna, Austria, last month.

Around 850 AD, the Byzantine Empire regained control and all traces of the nomads disappeared. Reforestation took place in its place.

The discovery provides rare evidence of the existence of nomadic tribes in a specific place and time, Izdebski said. “We know very little about their history because states have shown no interest in recording them.”

Historians didn't write about nomads because they weren't part of the elite, he says. Additionally, nomadic tax records exist because it was difficult for nomads to pay taxes. Tax records can be a rich source of information about past populations.