It is unusual to find side chairs with continuous humpback crestrails, as most examples with such rails protrude beyond the side rails. It is much more common to find armchairs of this continuous rail type.
Several examples of side chairs with protruding crestrails, known as dengguayi, are published. See Wang Shixiang et. al., Connoisseurship of Chinese Furniture: Ming and Early Qing Dynasties, vol. II, Hong Kong, 1990, p. 37, nos. A54 and A57. See, also, the side chair dated to the late 17th century, illustrated by R. Jacobsen, Classical Chinese Furniture in The Minneapolis Institute of Arts, pp. 54-5, no. 10, where the author states that side chairs were made in sets and kept readily available against the walls of the house until they were needed.