Final answer:
China's unity over millennia was achieved through the Mandate of Heaven, Confucian cultural values, and bureaucratic governance which together helped to maintain continuity despite periods of political fragmentation.
Step-by-step explanation:
China maintained unity for millennia through a combination of political, ideological, and cultural strategies. Despite periods of division, certain core elements such as the Mandate of Heaven, the continuity of Confucian ideals, and a unified bureaucratic system played a crucial role in the country's unification.
The Mandate of Heaven established ideological continuity across dynasties, legitimizing new rulers while allowing for rebellion against oppressive governance. Cultural elements like ancestor worship, Confucian values, and seasonal rituals provided a sense of shared identity.
The country's bureaucratic institutions facilitated administrative and fiscal consistency. These structures, along with the integration of cultural diversity found in the multiple ethnic and cultural groups under the Qin and Han dynasties, helped maintain unity even through foreign rule and internal strife.