Emperors from the same family are classified in historical periods known as dynasties. Most of China's imperial rulers have commonly been considered members of the Han ethnicity, although recent scholarship tends to be wary of applying present day ethnic categories to historical situations. During the Yuan and Qing dynasties China was ruled by ethnic Mongols and Manchus respectively. The orthodox historical view sees these as non-native dynasties that became sinicized, though some recent scholars (such as those of the New Qing History school) argue that the interaction between politics and ethnicity was far more complex. Nevertheless, in both cases these rulers claimed the Mandate of Heaven to assume the role of traditional Confucian emperors in order to rule over China proper.
During the Zhou dynasty, Chinese feudal rulers with power over their particular fiefdoms were called gong (公) but, as the power of the Shang and Zhou kings (王, OC *ɢʷaŋ, mod. wang) waned, the dukes began to usurp that title for themselves.
In 221 BC, after the then-king of Qin completed the conquest of the various kingdoms of the Warring States period, he adopted a new title to reflect his prestige as a ruler greater than the rulers before him. He called himself Shi Huangdi, the First Emperor. Before this, Huang (皇) and Di (帝) were the nominal "titles" of eight rulers of Chinese mythology or prehistory: The three Huang (皇, OC *ɢʷˤaŋ, "august, sovereign") were godly rulers credited with feats like ordering the sky and forming the first humans out of clay; the five Di (帝, OC *tˤeks, also often translated "emperor" but also meaning "the God of Heaven") were cultural heroes credited with the invention of agriculture, clothing, astrology, music, etc. In the 3rd century BC, the two titles had not previously been used together. Because of the god-like powers of the Huang, the cult worship of the Di, and the latter's use in the name of the God of Heaven Shangdi, however, the First Emperor's title would have been understood as implying "The Holy" or "Divine Emperor". On that account, some modern scholars translate the title as "thearch".
On occasion, the father of the ascended emperor was still alive. Such an emperor was titled the Tai Shang Huang (太上皇), the "Grand Imperial Sire". The practice was initiated by the First Emperor, who gave the title as a posthumous name to his own father. Liu Bang, who established the Han dynasty, was the first to become emperor while his father yet lived. It was said he granted the title during his father's life because he would not be bowed to by his own father, a commoner.
Owing to political fragmentation, over the centuries, it has not been uncommon to have numerous claimants to the title of "Emperor of All China". The Chinese political concept of the Mandate of Heaven essentially legitimized those claimants who emerged victorious. The proper list was considered those made by the official dynastic histories; the compilation of a history of the preceding dynasty was considered one of the hallmarks of legitimacy, along with symbols such as the Nine Ding or the Heirloom Seal of the Realm. As with the First Emperor, it was very common also to retroactively grant posthumous titles to the ancestors of the victors; even in Chinese historiography, however, such grants were not considered to elevate emperors prior to the successful declaration of a new dynasty.