Complex sentence: Wales endured great economic and cultural changes in the early 20th century, with the boom Edwardian years (which saw population growth exceed 20 per cent) followed by war, economic uncertainty and numerous industrial disasters.
Split into simpler sentences: Wales endured great economic and cultural changes in the early 20th century. The boom Edwardian years saw population growth exceeded 20 per cent, but this was followed by war, economic uncertainty and numerous industrial disasters.