Complex sentence: Pu Songling was a Qing dynasty author active in the seventeenth century; homosexuality in China was already commonplace by that time, but was regarded as a taboo and "off-centre" practice.
Split into simpler sentences: Pu Songling was a Qing dynasty author active in the seventeenth century. Homosexuality in China, though commonplace, was regarded as a taboo and "off-centre" practice.