It was from one of Mali's former conquests, the kingdom of Gao, that the last major empire of the western Sudan emerged. Although the city of Gao had been occupied by a Songhai dynasty prior to being conquered by Mansa Musa's forces in 1325, it was not until much later that the Songhai empire emerged. The empire saw its pre-eminent rise under the military strategist and influential Songhai king, Sonni Ali Ber. It began its rise in 1468 when Sonni Ali conquered much of the weakening Mali empire's territory as well as Timbuktu, famous for its Islamic universities, and the pivotal trading city of Djenné. Among the country's most noted scholars was Ahmed Baba—a highly distinguished historian frequently quoted in the Tarikh al-Sudan and other works. The people consisted of mostly fishermen and traders. Following Sonni Ali's death, Muslim factions rebelled against his successor and installed Soninke general, Askia Muhammad (formerly Muhammad Toure) who was to be the first and most important ruler of the Askia dynasty (1492–1592). Under the Askias, the Songhai empire reached its zenith.
Following Askia Muhammad, the empire began to collapse. It was enormous and could not be kept under control. The kingdom of Morocco saw Songhay's still flourishing salt and gold trade and decided that it would be a good asset.
The Dendi people are a subgroup of the Songhai.
The language, society and culture of the Songhai people is barely distinguishable from the Zarma people. Some scholars consider the Zarma people to be a part of and the largest ethnic sub-group of the Songhai. Some study the group together as Zarma-Songhai people. However, both groups see themselves as two different peoples.
The Songhai people have traditionally been a socially stratified society, like many West African ethnic groups with castes. According to the medieval and colonial era descriptions, their vocation is hereditary, and each stratified group has been endogamous. The social stratification has been unusual in two ways; it embedded slavery, wherein the lowest strata of the population inherited slavery, and the Zima, or priests and Islamic clerics, had to be initiated but did not automatically inherit that profession, making the cleric strata a pseudo-caste.
Louis Dumont, the 20th-century author famous for his classic Homo Hierarchicus, recognized the social stratification among Zarma-Songhai people as well as other ethnic groups in West Africa, but suggested that sociologists should invent a new term for West African social stratification system. Other scholars consider this a bias and isolationist because the West African system shares all elements in Dumont's system, including economic, endogamous, ritual, religious, deemed polluting, segregative and spread over a large region. According to Anne Haour – a professor of African Studies, some scholars consider the historic caste-like social stratification in Zarma-Songhay people to be a pre-Islam feature while some consider it derived from the Arab influence.
The different strata of the Songhai-Zarma people have included the kings and warriors, the scribes, the artisans, the weavers, the hunters, the fishermen, the leather workers and hairdressers (Wanzam), and the domestic slaves (Horso, Bannye). Each caste reveres its own guardian spirit. Some scholars such as John Shoup list these strata in three categories: free (chiefs, farmers and herders), servile (artists, musicians and griots), and the slave class. The servile group were socially required to be endogamous, while the slaves could be emancipated over four generations. The highest social level, states Shoup, claim to have descended from King Sonni 'Ali Ber and their modern era hereditary occupation has been Sohance (sorcerer). The traditionally free strata of the Zerma people have owned property and herds, and these have dominated the political system and governments during and after the French colonial rule. Within the stratified social system, the Islamic system of polygynous marriages is a norm, with preferred partners being cross cousins. This endogamy within Songhai-Zarma people is similar to other ethnic groups in West Africa.