What are some similarities between mali and songhai?

They were both African Muslim empires, they ruled over a similar region. They were both native to what is currently Mali. The Songhai could reasonably be called a successor empire to the Malinese. The Songhai had a single state language, (Gao) unlike the Malinese, and obtained greater power and wealth than the Malinese, but culturally there were a lot of similarities.