During the 19th Century, China developed a major opium addiction. They started trading for the drug with Britain in exchange for tea. With increasing demand for tea in Britain, China would send tea straight to London and receive exports of opium and cotton from India, whose foreign trade was dominated by the British at the time. Eventually, as the addiction increased,  the trade became unfavorable and unbalanced, so the Chinese cut off the opium trade.  And once the British Merchants started smuggling the drug, the Chinese limited all foreign trade to the Port of Canton. 

The British, unhappy, arrived at the Canton River in 1840 and started the war. And after two years, in 1842, the Chinese surrendered as the British had advanced to the Yangtze River. The British quickly took over Shanghai and forced the Chinese to sign treaties that gave Hong Kong to the British and allowed the British to have more trading rights.  

After other Western countries learned about this, they forced China to sign even more treaties, eventually leading to a second war with France and Britain, suppressing Chinese resistance and giving the West control over China through trade.

Other empires wanted the raw materials that China had, but China didn't want to trade much, so they established the "Canton System," which was a set of rules of engagement that heavily restricted the amount that other countries could trade with China.

Other countries, like the US, weren't happy, as they wanted things like silk that could only be produced there. They tried various methods to get China to trade with them, without much success. Because of this lack of trade, China fell behind in terms of money and power and didn't go through the industrial revolution that other countries did. This resulted in countries like Britain being very strong in terms of military, allowing them to engage in a war that the Chinese lost.

Unfair treaties were imposed on China for many years, severely damaging its economy. The Chinese government lost much control of its country, which was now basically in Britain's hands.

Now, in China, there was external influence from all the forced trades, and much internal instability. 

During this time, there was a lot of military opposition by the Chinese government, as well as peasant rebellions similar to the Taiping Rebellion. This rebellion was one in which the Western colonialist countries, such as Britain and France, heavily intervened militarily. However, rather than pushing down the peasants with their forces, they aided the Qing dynasty in repressing it themselves, aiming to protect their soldiers while also pursuing their interests in these trade markets.

Not only was the Taiping rebellion a struggle for the peasants, but it was a great example of how these different political, economic, and ethnic groups struggled for power. This was because the peasants' side was attacking through the Hakka-led Taiping forces, while the other side was the much richer Manchu-led Qing Dynasty. This just shows two of the many ethnic groups that fought for power and influence during their struggle for independence.