What actions of the Emperors of China can be justified and which ones can be condemned?

What actions of the Emperors of China can be justified and which ones can be condemned? Why were Japan and China closed?

1) China has always been one of the leading powers in the field of various reforms, in many respects this was facilitated by the reforms of the Chinese emperors, who did everything to increase the potential of their power. But there were also rather dubious methods of reformation – reprisals against reformers.

2) The self-isolation of Japan and China largely depended on the influx of Europeans into these countries. Increased internecine wars between feudal lords and the income from foreign trade could undermine the feudal system of these countries.