The ended in 221 BCE, after the state of conquered the ot her six kingdoms and established the first unified Chinese state. Qin Shi , the emperor of Qin, proclaimed himself the "First Emperor" (始皇帝) and imposed reform s throughout China, notably the forced standardization of the Chinese language, me asurements, length of cart axles, and currency. The Qin Dynasty lasted only fifteen y ears, falling soon after Qin Shi Huang's death, as its harsh legalist and authoritarian policies led to widespread rebellion.[46][47]

The subsequent Dynasty ruled China between 206 BCE and 220 CE, and create d a lasting Han cultural identity among its populace that has endured to the present day.[46][47] The Han Dynasty expanded the empire's territory considerably with mili tary campaigns reaching Korea, Vietnam, Mongolia and Central Asia, and also helpe d establish the Silk Road in Central Asia. Han China gradually became the largest ec onomy of the ancient world.[48] The Han Dynasty adopted Confucianism, a philosop hy developed in the , 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.[49]

The Great Wall of China was built by several dynasties over two thousand years to p rotect the sedentary agricultural regions of the Chinese interior from incursions by nomadic pastoralists of the northern steppes After the collapse of Han, a period of disunion known as the period of the Three Kin gdoms followed.[50] In 581 CE, China was reunited under the Sui. However, the Sui Dynasty declined following its defeat in the Goguryeo–Sui War (598–614).[51][52]

Under the succeeding Tang and dynasties, Chinese technology and culture ent ered a golden age.[53] The An Shi Rebellion in the 8th century devastated the count ry and weakened the dynasty.[54] The Song Dynasty was the first government in wor ld history to issue paper money and the first Chinese polity to establish a permanent standing navy.[55] Between the 10th and 11th centuries, the population of China do ubled in size to around 100 million people, mostly due to the expansion of rice cultiv ation 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,[56] an d social elites gathered to view art, share their own and trade precious artworks. Th Song Dynasty saw a revival of Confucianism, in response to the growth of Buddhis m during the Tang.[57]

Detail from Along the River During the Qingming Festival, a 12th-century painting s howing everyday life in the Song Dynasty's capital city, Bianjing (today's Kaifeng) 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 th e last remnant of the Song Dynasty in 1279. Before the Mongol invasion, the populat ion of Song China was 120 million citizens; this was reduced to 60 million by the tim e of the census in 1300.[58] A peasant named Zhu Yuanzhang overthrew the Yuan D ynasty in 1368 and founded the Ming Dynasty. Under the Ming Dynasty, China enjoy ed another golden age, developing one of the strongest navies in the world and a ric h and prosperous economy amid a flourishing of art and culture. It was during this p eriod that He led explorations throughout the world, reaching as far as Africa. [59] In the early years of the Ming Dynasty, China's capital was moved from Nanjing to Beijing. During the Ming Dynasty, philosophers such as Wang Yangming further c ritiqued and expanded Neo-Confucianism with concepts of individualism and innate morality.[60] In 1644, Beijing was captured by a coalition of rebel forces led by Li Zicheng, a mino r Ming official who led the peasant revolt. The last Ming Chongzhen Emperor commi tted suicide when the city fell. The Manchu Qing Dynasty then allied with Ming Dyn asty general Sangui and overthrew Li's short-lived Shun Dynasty, and subsequen tly seized control of Beijing, which became the new capital of the Qing Dynasty.