What political changes occurred in china?

Answer

easy: comunism

It should be noted that the ending of what was called the Age of Imperialism, occurred roughly around the time of the beginning of WWI.

Starting a little earlier in about 1911, China went into a protracted period of civil war and revolution which eventually culminated in the formation in 1949 of what we now recognize as the Peoples Republic of China. (PRC)

Prior to that China had itself been an imperialistic society ting Asia until it gradually failed and became a weak society controlled by royalty and fell to being a slavish colony of Britain. Compared to this, the switch to communism was a great improvement in many ways for the average person.( no more emperor, no more tion by foreign royalty)

This form of government gradually improved the lots of the people and they are now enjoying great financial success ,but fewer personal rights and freedoms than other democratic forms of capitalistic governments. The form of communism they adopted evolved differently from the communism of Russia and has had a different result.

So, one may not say simply that they just became communist, since that term is often misunderstood and has different meanings in different places and at different times.