Final answer:
Hausaland or a collection of African states existed in modern-day Nigeria from 1000 to 1800 CE, with Islam playing an influential role in the region's development. The Songhai Empire, including Hausaland, was an example of the advanced societal development in pre-colonial West Africa. Hausaland saw decline with the Fulani invasions in the early 19th century.
Step-by-step explanation:
The region referred to as Hausaland, also known as a collection of African states, existed in what is now modern-day Nigeria from around 1000 to 1800 CE. During this period, Hausaland was part of a larger context of West African history. It saw the rise and fall of several powerful empires, cultures, and trade networks, with Hausaland often serving as a vital trade link connecting various parts of the African continent to the larger world.
Hausaland was influenced by the rise of Islam, and by the end of the fourteenth century, many rulers from Mali to Hausaland had adopted the religion. In the Songhai Empire, which stretched from the Atlantic coast to Hausaland and beyond to the north, Islam became deeply entrenched. The introduction of Islam brought new educational systems, centralized governments, and long-distance trade routes which were fundamental to the region's development.
Fulani invasions in the early 19th century marked the decline of these states in Hausaland. Hausaland's complexity and the sophisticated systems that had been developed such as bureaucracy, state law, and infrastructure exemplify the advanced level of state development in West African societies prior to European colonization.