Guangdong is the wealthiest province in China. Sitting next to Hong Kong and located far from the capital city, the people of Guangdong have a history of ignoring instructions from Beijing, something that undermines CPC authority.
Although hugely successful economically, Guangdong also encompasses everything that can go wrong with a capitalist system, for example crime and corruption. As the province is one of the most crucial to China's economic success, it is important that the CPC leadership in Guangdong are not seen to be above the law or lining their pockets at the expense of the state.
In recent years Beijing has been forced to intervene in Guangdong. With public protests over land seizures or rising unemployment, the Chinese authorities do not want social unrest to develop into widespread political unrest. In 2015, thousands of officials, including many high ranking CPC members, were investigated in an anti-corruption crackdown.