I want to know the answer to the following question:
How long had Nanjing been the capital city of Yangzhou?
All the background I'm provided with is that "In the late period of Shang dynasty, Taibo of Zhou came to Jiangnan and established Wu state, and the first stop is in Nanjing area according to some historians based on discoveries in Taowu and Hushu culture.". Is that enough to answer the question?
Answer: no