The remains of 86 people hailing from across Europe have been uncovered beneath a Welsh college.
The remarkable haul of skeletons was found under Coleg Menai’s Pencraig Campus in Llangefni, Angelsey.
Experts examining the bones believe the earliest dates back 1,600 years, just after the Romans left Wales in a bid to fight off barbarian invaders from their territory in modern France.
Dr Irene Garcia Rovira of Archaeology Wales said the remains were classified as 'early medieval', Wales Online reported .
She added: "The cemetery could date back from the 4th century to the 8th century.
"In Anglesey, the soil is every acidic, so to have this kind of preservation is very unique."
What is particularly curious about the find is the sheer distance people seem to have travelled to get to Wales.
Dr Rovira said: "What we do know from the isotope analyses is that some individuals came from western Britain, where the border is today between England and Wales, a couple from Scandinavia and a couple from Mediterranean places like Spain."
Amongst the mass grave were the remains of significantly more males than females, although the proportion may even out when the findings are paired with Brython Archaeology's records of a previous dig.
Alongside the bodies - which were found in stone-lined graves - were Roman coins from the 2nd century AD and a Celtic brooch.
Dr Rovira, said: "It could be that it just happened to be on the soil at the time of the burial and fell into the grave, or it could have been purposely placed with her, as some sort of family hairloom.
"But it's not clear yet, you could go with either theory. It's a bit of a mystery.
"One side has the face of Antoninus Pius but the other side is very abrasive.
"The broach is an early medieval item that could have been attached to someone that was buried, but we don't know much about it."
