Complex sentence: On the mainland, after declining in popularity after the 1920s, the Mulian opera revived after being listed as a National Intangible Cultural Heritage in 2006, but even supporters in the People's Republic see the future as under threat from high-tech television and films.
Split into simpler sentences: On the mainland, after declining in popularity after the 1920s, the Mulian opera revived when it was listed as a National Intangible Cultural Heritage in 2006. But even supporters in the People's Republic see the future as under threat from high-tech television and films.