China has eight regional languages that are mutually unintelligible, and many true dialects. The system appears to work mainly because as many as 70% speak Mandarin. Fluency in Chinese reading and writing is undoubtedly difficult to achieve, and this must act as a brake on the drive for literacy. There have been a number of attempts to reform or simplify the system. The most radical in Pinyin, which is a program to replace Chinese characters with an alphabetic system. This was supported by Mao, but faltered after his death.