In aztec society, a person’s social class was fixed; rank was determined at birth, and there was no possibility of moving up the social hierarchy.

Actually, that's false. The Aztecs had two distinct social classes: the macehualles or commoners, and the nobility or pilli. The ranks were not determined by birth as one could rise from the macehualles to pilli through great skill and bravery during war

(202 bc - 220 ad) dynasty started by lui bang; a great and long-lasting rule, it discarded the harsh policies of the qin dynasty and adopted confucian principles; han rulers chose officials who passed the civil service exams rather than birth; it was a time of prosperity

north atlantic treaty organization.