Complex sentence: During the Mid 18th century there was an expansion of jade mining and its subsequent export to China as a result of increased Chinese influence over the region, the discovery of new jade quarries, and growing demand for the gem among wealthy Chinese.
Split into simpler sentences: During the mid-eighteenth century there was an expansion of jade mining and and an increase in exports to China. This was a result of increased Chinese influence over the region, the discovery of new jade deposits, and growing demand for the gem among wealthy Chinese.