While the Xia dynasty is typically considered to be the first orthodox Chinese dynasty, numerous sources including the Book of Documents mention two other dynasties that preceded the Xia: the "Tang" (唐) and the "Yu" (虞) dynasties.[2][3][4][5] The former is sometimes called the "Ancient Tang" (古唐) to distinguish it from other dynasties named "Tang".[6] Should the historicity of these earlier dynasties be attested, Yu the Great would not have been the initiator of dynastic rule in China.
Some historians consider AD 303, the year in which the Emperor Jing of Cheng-Han declared the era name "Jianchu" (建初), to be the start of the Cheng-Han.[197] Accordingly, the Cheng-Han was founded by the Emperor Jing of Cheng-Han and lasted 44 years.
Some historians consider AD 1260, the year in which the Emperor Shizu of Yuan was proclaimed "Khagan of the Great Mongol State" and declared the era name "Zhongtong" (中統), to be the start of the Yuan dynasty.[265] Accordingly, the Yuan dynasty lasted 108 years.
Traditional Chinese historiography considers the Northern Yuan to have ended in either AD 1388 or AD 1402 when the dynastic name "Great Yuan" was abolished.[269][270] Accordingly, the Northern Yuan lasted either 20 years or 34 years, and its last ruler was either the Tianyuan Emperor or the Örüg Temür Khan. However, some historians regard the Mongol-ruled regime that existed from AD 1388 or AD 1402 up to AD 1635—referred to in the History of Ming as "Dada" (韃靼)—as a direct continuation of the Northern Yuan.[271]