Complex sentence: Sunderland had suffered badly from unemployment during the Great Depression of the early 1930s, but then fell over the coming decades as new industries sprung up and jobs were readily available in skilled trades which played a huge role in the continuing rebuilding of the town.
Split into simpler sentences: Sunderland had suffered badly from unemployment during the Great Depression of the early 1930s, but then improved over the subsequent decades as new industries sprung up. Jobs were readily available in skilled trades and this played a role in the continuing rebuilding of the town.