Why didn't Chang 'an Painting School have Zhang Sanyou?

There is no Zhang Sanyou in Chang 'an School of Painting, but he is from Shaanxi, and everyone thinks he is a Shaanxi School of Painting. In fact, he is the second generation leader of Chang 'an Painting School. Zhang Sanyou was born in Dali in 1940, and graduated from Xi Academy of Fine Arts in 1963. He used to be the director of Chinese painting in Xi Academy of Fine Arts. He studied under Li Keran, who is a century-old master, and is good at landscapes, flowers and birds, and figures. He is recognized as the second generation leader of Chang 'an Painting School.