This is a complex question with a difficult answer. Gao and the surrounding territories, which formed the metropole of the Songhai state, were vassals of Mali until the mid-15th century. The ruling elite of the Songhai state were not Mande-speakers, unlike the ruling elite of Mali. In fact, Songhai (Sonrai/Zarma) is usually classified as a Nilo-Saharan language rather than a Niger-Congo language (although this obscures the fact that both Songhai and Mande are highly complex languages overlapping in a few ways, probably through adoptions and sharing).

Gao achieved its independence from Mali in 1355 under the rule of Sulaiman-Mar, who was arguably a viceroy who seized power from the Dia Kings (who had seemingly been somewhat content with an affiliation with Mali). Then, as the Mande/Mali hegemony of the region began to decline, Sulaiman-Mar's descendants took on more and more responsibility for leadership in the region. In 1486, a Mossi force from the south threatened the city of Timbuktu, which was technically a vassal of Mali. When the Mande kings were unable to defend it, the Songhai ruler Sunni Ali Ber (descendant of Sulaiman-Mar) stepped in and succesfully defended it. Over the following two decades he successively conquered most of the other vassals of Mali as well as independent groups such as the Dogon cultivators and Fulani(Peul) agriculturalists of the region. By the end of the 15th century, Songhai controlled much of the eastern section of the West African Sahel and also the inland delta of the Niger River, meaning that it had achieved a certain regional hegemony.

Many of the core features of Mali passed on to Songhai, including sponsorship of learning (the University of Sankore, for example) and especially of Islamic leadership (Askia Muhammad was the first ruler of Songhai to make the hajj, and was appointed Caliph of western Sudan), as well as control over gold trade into northern Africa. However, its leadership were quite culturally distinct from that of Mali.