Archaeologists with the Stonehenge and Avebury World Heritage Site have identified 415 ancient ditches in a single square-mile area surrounding the iconic English monument. The group was conducting a geophysical survey of the land when they made the discovery, according to Gizmodo.

Researchers say the ditches predate Stonehenge by thousands of years and indicate that hunter-gatherer communities spent time there in the early Mesolithic period when what is now Britain was repopulated after the last Ice Age.

The study was published earlier this month in the Journal of Archaeological Science. Co-author Nick Snashall said the team of scientists used “new geophysical techniques” such as an electromagnetic surveyor, which helps measure how electric fields travel through dirt, in combination with “coring and pin point excavation” in order to reveal “some of the earliest evidence of human activity yet unearthed in the Stonehenge landscape.”

Inhabitants may have used the pits as a means to capture animals like boar, red deer, and aurochs, a now extinct wild cattle species. Paul Garwood, senior lecturer in prehistory at the University of Birmingham, said the discovery is not necessarily a “snapshot of one moment in time.”

“The traces we see in our data span millennia, as indicated by the 7,000-year timeframe between the oldest and most recent prehistoric pits we’ve excavated,” Garwood said. “From early hunter-gatherers to later Bronze Age inhabitants of farms and field systems, the archaeology we’re detecting is the result of the complex and ever-changing occupation of the landscape.”

The findings constitute the most recent and extensive Mesolithic discovery in the United Kingdom.