During the Zhou dynasty, a barbarian invasion drives the Zhou rulers eastwards. The state of Qin guards the western frontier, gradually moving eastward and occupying the original Zhou territory. Qin becomes a close ally of the Zhou.
King Ping of Zhou (770-720 BCE) transfers titles of nobility and huge estates to the chief of Qin. This elevation allows Qin to become more ambitious and better fend off attacks from surrounding regions.
The powerful Qin statesman Lord Shang Yang passes a number of reforms throughout the state. He promotes the strict political philosophy of Legalism and establishes the Qin capital at Xianyang.
King Ying Zheng, aged 12 or 13, becomes King of Qin. He will ultimately lead Qin to victory in the Warring States period.
During the Warring States period, Qin gradually gains power through calculated attacks. When the final campaign to unify China begins around 230 BCE, Qin controls one-third of all the land under cultivation in China and one-third of China's total population.
Hoping to protect the country from invasion, Shi Huangdi orders that the previously-built portions of the Great Wall of China be connected into one long, unbroken structure.
After securing territories to the north, Shi Huangdi sends the majority of his army south to conquer southern tribes. He greatly expands the southern territories of the empire.
During his campaigns to the south, Shi Huangdi commences construction on the Grand Canal, which is used heavily for supplying and reinforcing troops during secondary campaigns.
As part of his Legalist political beliefs, Shi Huangdi requires that all books that do not support Legalism be destroyed. He orders these books to be burned, and only texts on farming, medicine, and predictions are saved.
Following several assassination attempts, Shi Huangdi becomes increasingly obsessed with death and the concept of eternal life. Evidence suggests he may have begun searching for an elixir of immortality.
On the advice of his chief advisor Li Siu, Shi Huangdi orders scholars to be executed on a large scale, since many scholars opposed his book burnings.
First Emperor Shi Huangdi dies on a journey through China. He is buried with an army of 8,000 terracotta warriors in his palace tomb.
Prime minister Li Siu contrives to place Hu Hai, the weak second son of Shi Huangdi, on the throne. Due to the weakness of Hu Hai, the oppressed people of China grow bolder and soon begin to revolt.