What are the main reasons that cause factories to shift from China to Vietnam?

During the past five years, Vietnam’s exports have doubled and compared to the previous year, total exports increased more than 13.6 percent. Vietnam is trying to attract manufacturing from Guangdong which is China’s traditional base. To realize that, Vietnam has reduced its corporate income tax rate to 22 percent and a further reduction to 20 percent is expected in 2016 which is 5 percent lower compared to China. Also, newly negotiated FTAs with South Korea, Russia, Belarus and Kazakhstan which will be finalized by the end of 2015, will also accelerate the expansion of its manufacturing industry.