Answer:
The major cause of ethnic tensions in Africa in the late 1900s was European colonization.
Step-by-step explanation:
During the late nineteenth century and early twentieth century, European colonization began in Africa. European countries— Britain, France, Belgium, Spain, Germany, Italy, and Portugal, colonized many parts of Africa between 1881-1914. With colonization, ethnic tensions increased in Rwanda between Tutsi and Hutu tribes. Hutu were the local populous tribe, whereas Tutsi were minorities. After Belgian colonized Rwanda and allowed native monarchs to rule over the local population. This created further conflicts and tensions between the two tribes.
After World War II, the political tables were turned in Hutu's favor and they drove Tutsi's out of the Rwanda. And, after Hutu President Juvénal Habyarimana's plane was shot dead, genocide of 800,000 Tutsi took place in Rwanda in the late 1900s.