Zhang Shiping was a merchant from Zhongshan during the late Han Dynasty period of Chinese history. Impressed by Liu Bei, he and Su Shuang sponsored Liu so he could have the funds to recruit a large troop of followers around 180... (wikipedia)
Mandarin has to be used as the main language, especially at school.
Getting to the stage where over half of the people can speak Mandarin is still a key success.
With improved transport, and with so many people moving around the country like never before, it is vital people are able to communicate with each other.
I understand why people feel strongly about their own dialects. We are not trying to stop people from speaking them at home or among friends.