<P> Birds in a Bamboo and Plum Tree Thicket, 12th century . </P> <Li> <P> The White Jasmine Branch, 12th century . </P> </Li> <P> The White Jasmine Branch, 12th century . </P> <Li> <P> Bamboos and Rock, by Li Kan (1244--1320) </P> </Li>

Why did the rulers of the tang and song dynasties support the arts and literature