Answer:
The Boxers or Boxer Rebellion was a movement in China held between 1899 and 1901 that was was an anti-imperialist, anti-Christian and anti-foreign.
There are two major causes of people joining the Boxers colonization of westerns in China after extreme weather conditions of drought and flood in Shandong province in 1897–1898 and rising anti-imperialist sentiment.
The second major reason was missionary activity in north China. After second opium war, foreign missionaries got freedom to deliver religious address and buy land to build churches anywhere in China.
These reasons raised anti-imperialist sentiment in China and people started joining the Boxers.