I think the answer is Sunni Ali. Sunni Ali organized a fleet to patrol the Niger river. During his reign, Songhai surpassed the height of the Mali Empire, engulfing areas under the Mali Empire (and the Ghana Empire before it). His death, in late 1492, is a matter of conjecture. According to the Tarikh al-Sudan, Ali drowned while crossing the Niger River.[3] Oral tradition believes he was killed by his sister's son, Askia Muhammad Ture. He was succeeded by his son, Sonni Baru, who was challenged by Askia because Baru was not seen as a faithful Muslim.[6] Askia succeeded to the throne. According to the Tarikh al-Sudan it is believed that this action caused Sonni Ali's sister to shout out "Askia!"(forceful one), at the news of this take over.