Why did China fail to avoid colonial conquests at the beginning of the modern era?

Why did China fail to avoid colonial conquests at the beginning of the modern era? How is this related to the peculiarities of the state structure?

China did not manage to avoid capture, because the policy of self-isolation, which was pursued in the country for quite a long time, contributed to this. This led to the fact that China lagged behind Western European countries and the United States of America in development. All this allowed the colonial countries to carry out their plans to establish control over the Chinese state and use it as a source for the extraction of raw materials. China from that time was divided into a number of provinces, which were controlled by various European countries.