China was in a constant period of unrest and turmoil after the Opium Wars and the Boxer Rebellion.
None of the new leaders and presidents could really consolidate their power in China and a struggle between the different warlords. broke out.
At the same time, China was eyeing a more prominent role within the international community and sent 150,000 workers to the Western Front as part of the Chinese Labour Corps.
The May 4th Movement of 1919 was born out of social contradictions of First World War and The Treaty of Versailles which led to the formation of the Chinese Communist Party.
Although not discussed in video above also study the New Culture Movement .