Answer:
China's decline in the nineteenth century
Explanation:
Opium wars was start of Century of Humiliation, China was forcefully moved from protectionist policy to free trade policy by British imperialist menace, Hong Kong wrongfully leased, and China's invincibility shattered. Imperialist from all side invaded to seize ports, Russia, France, Germany, Britain even more, Austro-Hungarians briefly on small scale. It was very uncool sad time.