Dioula is spoken by approximately twelve million people. Three million of them live in Burkina Faso, the rest in the neighboring countries. For most speakers in southwest Burkina Faso, the Dioula language is not their mother tongue, but is spoken readily in their daily life with people of other ethnic groups. It is very important as a trade language.

Some people describe Dioula as a simpler language or trade language of Bambara while others say that Dioula is related to Bambara as American English is related to British English. Some consider Dioula, Bambara and Malinke as the same language, implying that Dioula describes the same language in Côte d’Ivoire and in Burkina Faso and that Bambara and Malinke are names for the same language used in Mali. But, linguists consider each one as a distinct language, clearly identified as three languages of the Mandé family.

Source: Wikipedia
https://www.webonary.org/dioula-bf/?lang=en