Despite being counted as one of the 28 cities of Sub-Roman Britain, it seems that after the Romans left Britain in 410 Durovernum Cantiacorum was abandoned for around 100 years, except by a few farmers and gradually decayed. Over the next 100 years, an Anglo-Saxon community formed within the city walls, as Jutish refugees arrived, possibly intermarrying with the locals. In 597, Pope Gregory the Great sent Augustine to convert its King Æthelberht to Christianity. After the conversion, Canterbury, being a Roman town, was chosen by Augustine as the centre for his episcopal see in Kent, and an abbey and cathedral were built. Augustine thus became the first Archbishop of Canterbury. The town's new importance led to its revival, and trades developed in pottery, textiles, and leather. By 630, gold coins were being struck at the Canterbury mint. In 672, the Synod of Hertford gave the see of Canterbury authority over the entire English Church.