Tohan was the youngest son of Unkoku Toeki (1591-1644), with whom he studied. In 1655, Tohan collaborated on wall paintings for the imperial palace with his older brother Unkoku Toyo (1612-1668), along with Kano Tan'yu, Kano Yasunobu, Kaiho Yusho and Tosa Mitsuoki. In 1633, he was adopted by his brother Toyo and was thus in a position to suceed Toyo as head of the family after the latter's death. From that time on he called himself "Sesshu VI." He was awarded the honorary title Hogen (Eye of the Law; the second-highest honorary title given to painters) in 1675, giving a terminus post quem for the present pair of screens.
For other bird-and-flower screens by Tohan, see Yamaguchi Prefectural Museum of Art, ed., Unkokuha no keifu-Sesshu no kokeisha tachi (Genealogy of Unkoku school: successors of Sesshu) (Yamaguchi: Yamaguchi Prefectural Museum of Art, 1986), pl. 31.