Was China’s decline in the nineteenth century due more to internal problems or to Western imperialism?

In 1800 most Chinese had no reason to question the concept of China as the central kingdom. No other country had so many people; Chinese products were in great demand in foreign countries; and the borders had recently been expanded. A century later China’s world standing had sunk precipitously. In 1900 foreign troops marched into China’s capital to protect foreign nationals, and more and more Chinese had come to think that their government, society, and cultural values needed to be radically changed.