<P> Sonni Ali, a Songhai, began his conquest by capturing Timbuktu in 1468 from the Tuareg . He extended the empire to the north, deep into the desert, pushed the Mossi further south of the Niger, and expanded southwest to Djenne . His army consisted of cavalry and a fleet of canoes . Sonni Ali was not a Muslim, and he was portrayed negatively by Berber - Arab scholars, especially for attacking Muslim Timbuktu . After his death in 1492, his heirs were deposed by General Muhammad Ture, a Muslim of Soninke origins . </P> <P> Muhammad Ture (1493--1528) founded the Askiya Dynasty, askiya being the title of the king . He consolidated the conquests of Sonni Ali . Islam was used to extend his authority by declaring jihad on the Mossi, reviving the trans - Saharan trade, and having the Abbasid "shadow" caliph in Cairo declare him as caliph of Sudan . He established Timbuktu as a great center of Islamic learning . Muhammad Ture expanded the empire by pushing the Tuareg north, capturing Aïr in the east, and capturing salt - producing Taghaza . He brought the Hausa states into the Songhay trading network . He further centralised the administration of the empire by selecting administrators from loyal servants and families and assigning them to conquered territories . They were responsible for raising local militias . Centralisation made Songhay very stable, even during dynastic disputes . Leo Africanus left vivid descriptions of the empire under Askiya Muhammad . Askiya Muhammad was deposed by his son in 1528 . After much rivalry, Muhammad Ture's last son Askiya Daoud (1529--1582) assumed the throne . </P> <P> In 1591, Morocco invaded the Songhai Empire under Ahmad al - Mansur of the Saadi Dynasty to secure the goldfields of the Sahel . At the Battle of Tondibi, the Songhai army was defeated . The Moroccans captured Djenne, Gao, and Timbuktu, but they were unable to secure the whole region . Askiya Nuhu and the Songhay army regrouped at Dendi in the heart of Songhai territory where a spirited guerrilla resistance sapped the resources of the Moroccans, who were dependent upon constant resupply from Morocco . Songhai split into several states during the 17th century . </P> <P> Morocco found its venture unprofitable . The gold trade had been diverted to Europeans on the coast . Most of the trans - Saharan trade was now diverted east to Bornu . Expensive equipment purchased with gold had to be sent across the Sahara, an unsustainable scenario . The Moroccans who remained married into the population and were referred to as Arma or Ruma . They established themselves at Timbuktu as a military caste with various fiefs, independent from Morocco . Amid the chaos, other groups began to assert themselves, including the Fulani of Futa Tooro who encroached from the west . The Bambara Empire, one of the states that broke from Songhai, sacked Gao . In 1737, the Tuareg massacred the Arma . </P>

What important natural resources in west africa did the songhai empire control
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