The Warring States period ended in 221 BCE, after the state of Qin conquered the other six kingdoms and established the first unified Chinese state. Qin Shi Huang, the emperor of Qin, proclaimed himself the "First Emperor" (始皇帝) and imposed reforms throughout China, notably the forced standardization of the Chinese language, measurements, length of cart axles, and currency.
The Qin Dynasty lasted only fifteen years, falling soon after Qin Shi Huang's death, as its harsh legalist and authoritarian policies led to widespread rebellion. The subsequent Han Dynasty ruled China between 206 BCE and 220 CE, and created a lasting Han cultural identity among its populace that has endured to the present day.
The Han Dynasty expanded the empire's territory considerably with military campaigns reaching Korea, Vietnam, Mongolia and Central Asia, and also helped establish the Silk Road in Central Asia. Han China gradually became the largest economy of the ancient world.
The Han Dynasty adopted Confucianism, a philosophy developed in the Spring and Autumn period, as its official state ideology. Despite the Han's official abandonment of Legalism, the official ideology of the Qin, Legalist institutions and policies remained and formed the basis of the Han government.
After the collapse of Han, a period of disunion known as the period of the Three Kingdoms followed. In 580 CE, China was reunited under the However, the Sui Dynasty declined following its defeat in the Goguryeo–Sui War (598–614).
The Song Dynasty was the first government in world history to issue paper money and the first Chinese polity to establish a permanent standing navy. Between the 10th and 11th centuries, the population of China doubled in size to around 100 million people, mostly due to the expansion of rice cultivation in central and southern China, and the production of abundant food surpluses.
The Song Dynasty also saw a flourishing of philosophy and the arts, as landscape art and portrait painting were brought to new levels of maturity and complexity, and social elites gathered to view art, share their own and trade precious artworks. The Song Dynasty saw a revival of Confucianism, in response to the growth of Buddhism during the Tang.
In the 13th century, China was gradually conquered by the Mongol empire. In 1271, the Mongol leader Kublai Khan established the Yuan Dynasty; the Yuan conquered the last remnant of the Song Dynasty in 1279.
A peasant named Zhu Yuanzhang overthrew the Yuan Dynasty in 1368 and founded the Ming Dynasty. Under the Ming Dynasty, China enjoyed another golden age, developing one of the strongest navies in the world and a rich and prosperous economy amid a flourishing of art and culture.
It was during this period that Zheng He led explorations throughout the world, reaching as far as Africa. In the early years of the Ming Dynasty, China's capital was moved from Nanjing to Beijing. During the Ming Dynasty, thinkers such as Wang Yangming further critiqued and expanded Neo-Confucianism with concepts of individualism and innate morality.
In 1644, Beijing was sacked by a coalition of rebel forces led by Li Zicheng, a minor Ming official who led the peasant revolt. The last Ming Chongzhen Emperor committed suicide when the city fell. The Manchu Qing Dynasty then allied with Ming Dynasty general Wu Sangui and overthrew Li's short-lived Shun Dynasty, and subsequently seized control of Beijing, which became the new capital of the Qing Dynasty.(wikipedia.org)