Following the end of Roman rule in its province of Britannia in the early 5th Century, the northeastern coast was raided by the Angles from across the North Sea in Scandinavia. They subsequently began crossing the North Sea and settled in the area, creating the Kingdom of Northumbria in Sub Roman Britain. Hartlepool began as an Anglian settlement, and a town developed in the 7th Century A.D. sited around Hartlepool Abbey, which had been founded in 640 A.D. by the Irish Christian priest Saint Aidan upon a headland overlooking a natural harbour and the North Sea. The monastery became powerful under St Hilda, who served as its abbess from 649–657 A.D. The Abbey fell into decline with the loss of Northumbrian power in the early 8th Century, and it was probably destroyed during a sea raid by Vikings on Hartlepool in the 9th Century. In March 2000, the archaeological investigation television programme "Time Team" located the foundations of the lost monastery in the grounds of St Hilda's Church.