The Qin and Han Dynasties in China

The Qin dynasty was the first dynasty of Imperial China, lasting from 221 to 206 BCE. Named for its heartland in Qin state, the dynasty was founded by Qin Shi Huang, the First Emperor of Qin. The strength of the Qin state was greatly increased by earlier Legalist reforms. In the mid and late third century BCE, the Qin state carried out a series of swift conquests, first ending the powerless Zhou Dynasty and eventually conquering the other six of the Seven Warring States. Its 15 years was the shortest major dynasty in Chinese history, consisting of only two emperors, but inaugurated an imperial system that lasted from 221 BCE all the way until 1912 CE! 

The Qin wanted to create a unified country with a central power and a large military. The central government took power away from aristocrats and landowners to gain direct control over the peasants, who were the majority of the population. This allowed several ambitious projects involving over 300,000 peasants and convicts.

The most famous project was building and connecting walls along the northern border, eventually developing into the Great Wall of China. Another major project was a massive new national road system, as well as the city-sized Mausoleum of the First Qin Emperor guarded by the life-sized Terracotta Army.

When the first emperor died in 210 BCE, different groups fought for power. Popular revolt broke out and the weakened empire soon fell. After a brief warring period, the rebel leader Liu Bang gained power and founded the Han dynasty. The Han became China's second dynasty and ruled from 202 BCE–220 CE. The Han period is considered a golden age in Chinese history. To this day, China's majority ethnic group refers to themselves as the "Han Chinese" and the Chinese script is referred to as "Han characters".

Liu Bang became known as Emperor Gaozu of Han and was at the pinnacle of Han society. He presided over the government but shared power with both the nobility and appointed ministers who came largely from the scholarly gentry class. The Han Empire was divided into areas directly controlled by the central government. These kingdoms, however, gradually lost their independence. A later Han Emperor Wu (141–87 BCE) began to allow Confucianism to guide education and court politics.

The Han dynasty saw an age of economic prosperity and growth.  The coinage issued by the central government mint in 119 BCE remained the standard coinage of China until the Tang dynasty over 700 years later. The period saw a number of innovations. To finance its military campaigns and the settlement of newly conquered territories, the Han government nationalized the salt and iron industries in 117. Science and technology during the Han period saw significant advances, including the process of paper making, the nautical steering ship rudder, the use of negative numbers in mathematics, the raised-relief map, and a seismometer employing an inverted pendulum that could be used to discern the cardinal direction of distant earthquakes.

Military campaigns expanded Han control into Central Asia and helped establish the trade network known as the Silk Road, which reached as far as the Mediterranean world. Emperor Wu also launched successful military expeditions in the south and into the Korean Peninsula.

After 92 CE, court politics and violent power struggles between the various supporters of the empresses and empresses dowager, began the Han's ultimate downfall. Imperial authority was also seriously challenged by large Daoist religious societies which instigated several rebellions. The last Han Emperor Xian was overthrown in 220 CE.