Complex sentence: Cedd founded many churches and monasteries at Tilbury and Ithancester and went on to found the Monastery of Lastingham in his native Northumbria at the request of the new king, Aethelwald.
Split into simpler sentences: Cedd founded many churches and monasteries at Tilbury and Ithancester. Later he went on to found the Monastery of Lastingham in his native Northumbria at the request of the new king of Northumbria, Aethelwald.