Query: Nanjing's railway is important, and is located in what region of China?
Context: Nanjing is an important railway hub in eastern China. It serves as rail junction for the Beijing-Shanghai (Jinghu) (which is itself composed of the old Jinpu and Huning Railways), Nanjing–Tongling Railway (Ningtong), Nanjing–Qidong (Ningqi), and the Nanjing-Xian (Ningxi) which encompasses the Hefei–Nanjing Railway.