I want to know the answer to the following question:
What was Sichuan referred to as by ancient Chinese sources?
All the background I'm provided with is that "Throughout its prehistory and early history, the region and its vicinity in the Yangtze region was the cradle of unique local civilizations which can be dated back to at least the 15th century BC and coinciding with the later years of the Shang and Zhou dynasties in North China.". Is that enough to answer the question?