After the People's Republic of China took control of Mainland China in 1949, the Republic of China government based in Taiwan continued to control the Dachen Islands off the coast of Zhejiang until 1955, even establishing a rival Zhejiang provincial government there, creating a situation similar to Fujian province today. During the Cultural Revolution (1966–76), Zhejiang was in chaos and disunity, and its economy was stagnant, especially during the high tide (1966–69) of the revolution. The agricultural policy favoring grain production at the expense of industrial and cash crops intensified economic hardships in the province. Mao’s self-reliance policy and the reduction in maritime trade cut off the lifelines of the port cities of Ningbo and Wenzhou. While Mao invested heavily in railroads in interior China, no major railroads were built in South Zhejiang, where transportation remained poor.

Answer this question, if possible (if impossible, reply "unanswerable"): What happened from 1955-1977?
unanswerable