Bantu and its related languages began spreading about 4000 years ago from the country that is today known as?

Bantu was said to originate in West Africa, the Cameroon, and migrated into Southern and East Africa.  Joseph Greenberg in 1960, however,  proposed that Bantu and its related languages had spread to east and south from Nigeria. About 4000 years ago from the country that is today known as Nigeria. 

i don't see how you want other people to do your work for you and it is like you are just handing your assignment to anybody else and having them deal with it instead of your self i thought this site was for asking questions and somebody could you on it not just handing your work to somebody else to deal with it just saying don't mean to be mean just proving a fact.

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answer; i believe that the correct answer is (chronological order);