Present-day Scotland has much to thank the Picts for. If the indigenous inhabitants of the area hadn’t repulsed the Romans and, later, the Germanic Angles invaders, it’s unlikely we would think of Scotland as its own independent culture and region. Despite their historical importance, though, archaeologists today know very little about the Picts, which are sometimes described as one of Europe's lost peoples. But a new dig of an old fort at Burghead in Moray, Scotland, is yielding some new clues reports the BBC.

What researchers do know about the Picts comes from the writings of the Romans and the Angles as well as some stone carvings and artifacts from archaeological sites. Historians aren’t even sure what the loose confederation of tribes called themselves, since pict is likely derived from the Latin picti or the “painted ones” which the Romans called them due their practice of tattooing and painting their bodies for battle. The Picts show up for the first time in the written record in 297 B.C. and are depicted as a late Iron Age and early Medieval powerhouse, ruling the east and north of Scotland. By 900 A.D., however, written records stopped mentioning them, and they were likely swallowed up by the emerging Gaelic culture.

Tia Ghose at LiveScience reports that local people knew about the site of the Pictish fort at Burghead since the Middle Ages. According to the Burghead Visitor’s Centre, excavations at the site took place in the 19th century. Researchers uncovered walls 26 feet thick and almost 20 feet high, with boulders in the foundation. It was believed the walls were built around 400 A.D. and destroyed by fire around 800 or 900 A.D.

Researchers in 1809 also cleared out a structure now known at the Burghead Well, a flight of steps leading into an underground chamber containing a tank fed by springs. Researchers believe it had a ceremonial significance and might have been used to execute people by drowning.

According to a press release, researchers think Burghead Fort was a major seat of Pictish power between 500 and 1,000 A.D., but while an underground well was discovered there in the 1800s, archaeologists long thought that most artifacts from the Picts had been destroyed in the years since.

Then, in 2015, researchers from the University of Aberdeen decided to dig at the site to see if anything was left. Now, they have uncovered the remains of a Pictish longhouse containing a well-built stone hearth as well as a coin from the time of Alfred the Great, King of Wessex from 871 to 899, indicating that the site was still in use at that time.

“The assumption has always been that there was nothing left at Burghead; that it was all trashed in the 19th century but nobody’s really looked at the interior to see if there’s anything that survives inside the fort,” archaeologist Gordon Noble of the University of Aberdeen says in the release. “But beneath the 19th century debris, we have started to find significant Pictish remains… Overall these findings suggest that there is still valuable information that can be recovered from Burghead which would tell us more about this society at a significant time for northern Scotland – just as Norse settlers were consolidating their power in Shetland and Orkney and launching attacks on mainland Scotland.”

The longhouse will help researchers learn about the architecture and construction methods used by the Picts, and further excavations may reveal even more about the little-understood culture.

“[Burghead’s] significance has just increased again though with this discovery. The fact that we have surviving buildings and floor levels from this date is just incredible,” Bruce Mann, archaeologist for Aberdeenshire Council Archaeology Service, says in the release. “And the universities’ work is shedding light on what is too often mistakenly called the ‘Dark Ages’.”

Burghead is not the only Pictish site archaeologists are looking at. In fact, there is currently a big push to discover Pictish sites led by Noble through his Northern Picts Project. In recent years, researchers have uncovered an unknown royal center at Rhynie, a silver hoard at Gaulcross and a fort on top of a sea stack known as Dunnicaer.