The Qing Dynasty continued to rule strongly until near the end of the 1700s AD. In 1735, the Yongsheng Emperor died and his son, the 24-year-old Qianlong Emperor, took power. Like his father and grandfather, Qianlong kept power in his own hands.
Qianlong took advantage of the weakness of Central Asian kingdoms and the collapse of the Safavids in West Asia to send his army further west and conquer a lot of Central Asia, including the Uighurs in 1759 AD. He also got more control over Tibet and Nepal, to the south. But when he tried to conquer further south into Burma, Thailand, and Vietnam, his army lost.
As Qianlong’s army got weaker, Chinese traders were selling more and more tea, porcelain, and silk to Britain every year. British people loved these things. They were willing to pay a lot of money for them. But Britain needed something to trade to people in China in exchange, and they weren’t having any luck with that. What could they sell to China? British traders began to sell opium from India to people in China. Opium is an addictive drug, so once you got people addicted they would buy more and more opium. That worked great for Britain, but the government of China didn’t like everyone being on drugs!
By this time, Britain had gotten control of India, and British generals were looking for a way to get control of China too. They could not convince China to allow British traders to come and go the way they had in India – Qianlong and Jiaqing didn’t want British generals to rule China So the British generals kept on smuggling more and more illegal opium into China and getting more and more people addicted to opium.
Bibliography and further reading about the history of China: