Complex sentence: The first cycle occured from 1687 to the indepence wars and was caused by heavy demand in Peru and the second cycle in the mid 19th century fueled by the California and Australian gold rushes.
Split into simpler sentences: The first cycle occured from 1687 to the indepence wars and was caused by heavy demand in Peru. Second cycle started in the mid 19th century fueled by the California and Australian gold rushes.