He defined Qin and Former Han periods as ancient times, the time from Later Han through West Jin as the first transitional stage, and the time from the period of Sixteen Kingdoms through the middle of the Tang Dynasty as the middle period.
内藤は秦前漢時代を上古と規定し、後漢から西晋の間を第一次の過渡期とし、五胡十六国時代から唐の中期までを中世とする。