Internal and external factors of the Qing dynasty decline?
Corruption: The Dowager Queen made a right mess of things when
she took the real ruling power from her grandson, the true Emperor
who wanted to industrialize. The Dowager Queen took military
funding to build herself a grand Summer Palace, which practically
stopped Chinese military development. Her regressive beliefs
influenced well-known government officials, who ignored the cries
of starved commoners and sat behind their wall of riches,
delightfully unaware to the threat of Europeans.
Rise of Nationalism: Intellectuals saw the only way to defeat
the Europeans was to use European technologies against them, and
hence the overthrow of the corrupt and out-dated Imperialist Qing
Foreign invasion: The invasion by Europeans was made easy by
Qing Dynasty's backward military - the majority of the outnumbering
Chinese Navy was sunk in less than a week (what use were wooden
junks to steel monsters?). The British then subsequently supplied
opium to China, and when the Qing government refused to trade
opium, the Brits used it as an excuse to openly invade China, split
Chinese territories in unequal treaties, committed atrocious things
to the Chinese population and utterly undermined Qing rule.
Backward Imperialism: The last rulers of Qing Dynasty saw
themselves as divine rulers of a perfect nation, and saw European
inventions (such as the musket and cannons) to be useless dirt.
Therefore they didn't industrialize as the Japanese did (Meiji
Restoration), and therefore they seriously lacked behind.