Much of what came to constitute China Proper was unified for the first time in 221 B.C. In that year the western frontier state of Qin, the most aggressive of the Warring States, subjugated the last of its rival states. (Qin in Wade-Giles romanization is Ch’in, from which the English China probably derived.) Once the king of Qin consolidated his power, he took the title Shi Huangdi (First Emperor始皇帝), a formulation previously reserved for deities and the mythological sage-emperors, and imposed Qin’s centralized, nonhereditary bureaucratic system on his new empire. In subjugating the six other major states of Eastern Zhou, the Qin kings had relied heavily on Legalist scholar-advisers. Centralization, achieved by ruthless methods, was focused on standardizing legal codes and bureaucratic procedures, the forms of writing and coinage, and the pattern of thought and scholarship. To silence criticism of imperial rule, the kings banished or put to death many dissenting Confucian scholars and confiscated and burned their books (焚书坑儒). Qin aggrandizement was aided by frequent military expeditions pushing forward the frontiers in the north and south. To fend off barbarian intrusion, the fortification walls built by the various warring states were connected to make a 5,000-kilometer-long great wall (万里长城). What is commonly referred to as the Great Wall is actually four great walls rebuilt or extended during the Western Han, Sui, Jin, and Ming periods, rather than a single, continuous wall. At its extremities, the Great Wall reaches from northeastern Heilongjiang (黑龙江) Province to northwestern Gansu (甘肃).

A number of public works projects were also undertaken to consolidate and strengthen imperial rule. These activities required enormous levies of manpower and resources, not to mention repressive measures. Revolts broke out as soon as the first Qin emperor died in 210 B.C. His dynasty was extinguished less than twenty years after its triumph. The imperial system initiated during the Qin dynasty, however, set a pattern that was developed over the next two millennia.