However, a series of Sino-German agreements in 1934–1936 greatly accelerated railway construction in China. Major railways were built between Nanchang, Zhejiang, and Guizhou. The rapid developments could occur because Germany needed efficient transportation to export raw materials, and the railway lines served the Chinese government's need to build an industrial centre south of the Yangtze. In addition, the railways served important military purposes. For example, after the Hangzhou-Guiyang railway was built, military transport could pass through the Yangtze Delta Valley, even after Shanghai and Nanking were lost. Similarly, the Guangzhou-Hankou railway provided transport between the eastern coast and the Wuhan area and would later prove its worth in the early stages of the Second Sino-Japanese War.