Original: The three original settlements of Wearmouth (Bishopwearmouth, Monkwearmouth and Sunderland) had begun to combine, driven by the success of the port of Sunderland as well as the salt panning and the shipbuilding along the banks of the Wear.
Simplified: This was because of the success of the port of Sunderland as well as the salt panning and the shipbuilding along the banks of the Wear.