Generally the history of Korean painting is dated to approximately 108 C. E. , when it first appears as an independent form. Between that time and the paintings and frescoes that appear on the Goryeo dynasty tombs, there has been little research. Suffice to say that until the Joseon dynasty the primary influence was Chinese painting though done with Korean landscapes, facial features, Buddhist topics, and an emphasis on celestial observation in keeping with the rapid development of Korean astronomy. Throughout the history of Korean painting, there has been a constant separation of monochromatic works of black brushwork on very often mulberry paper or silk; and the colourful folk art or min-hwa, ritual arts, tomb paintings, and festival arts which had extensive use of colour. This distinction was often class-based: scholars, particularly in Confucian art felt that one could see colour in monochromatic paintings within the gradations and felt that the actual use of colour coarsened the p