Chinese history is so vast that identifying the major turning points would seem somewhat insignificant because there would be so many to list.

My suggestion would be to limit it: focus on certain dynasties, focus on certain historical subcategories (e.g. military history, STEM history, art history, etc).

In the 20th century some of the big ones would be:

The Xinhai revolution of 1911

The northern expedition of 1927

The Japanese invasion of China 1937

The Triump of the Communist Party 1949

The great leap forward 1958-1961

The Cultural Revolution: 1967-1976

Reform and Opening 1979-1990s

Tienanmen Square: 1989

Sorry, we don't allow throughout history questions. These tend to produce threads which are collections of trivia, not the in-depth discussions about a particular topic we're looking for. If you have a specific question about a historical event or period or person, please feel free to re-compose your question and submit it again. Alternatively, questions of this type can be directed to more appropriate subreddits, such as /r/history or /r/askhistory.