[Formation and shifting of TCM center].

Analysis is made on the so-called "Yuasa Phenomenon" in the history of Chinese medicine, which holds that, in the development of medical history, there exists a center of medical theory and practice representing the peak of development and orientation. Since the Song-Yuan dynasties, there was a process of constant changes and formation of medical center. This period had seen three separate TCM centers in Henan, Hebei and South of Yangtze River, discerning four stages, viz., inheritance, invention, renewal and unprecedented flourishing. This is a phenomenon not only reflecting the internal laws of medical development, but also deeply embodying the profound influence of social economy and culture on medicine.