When did the closed-door policy of the Qing Dynasty, which left China nearly 300 years behind, begin?

In 1723 (the first year of the Yongzheng era), due to the white-hot dispute with the Holy See over China's rituals, the Yongzheng emperor banned Catholicism, did not allow foreign missionaries to enter China to preach at home and restricted trade, which is seen as the beginning of the lockout.

By 1757 (the twenty-second year of the Qianlong era), the Qianlong emperor sent a decree from the capital to the coastal provinces, ordering that, in addition to Guangzhou, stopping Xiamen, Ningbo and other ports of the Western trade, which is known as the "one mouth of commerce" policy.

The idea that the Qing dynasty practiced a policy of "closed-door self-defense" or "closed-door lockout" originated with British merchants who were trying to sell their goods (especially opium) to China, and was accepted by Marx in his writings. In the 1950s, it was incorporated into the dominant ideology of China, written into textbooks, and a view was formed that the Qing Dynasty was "closed to the outside world".

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The closed-door policy, which refers to a national policy of closing the country to the outside world, is typical of isolationism. It strictly limited exchanges with the outside world in economic, cultural, and scientific fields, and as a result, China's overall national strength and development lagged behind that of Western countries.

The positive effect was to combat and limit to a certain extent the rampant smuggling and piracy at sea. It played a positive role in stabilizing the coastal areas. It also played a role in self-defense against the aggressive activities of Western colonizers.

The negative impact is that the long-term implementation of this policy, hindering the Sino-foreign relations, affecting China's absorption of advanced culture and science and technology, resulting in China's isolation from the world, and seriously hampered the development of the sprouting of capitalism. It made China out of touch with the world and slowly lagged behind the world.

Reference:Baidu encyclopedia Closed country