Which group invaded the empire of songhail? how were they able to defeat songhai?

After the passing of Emperor Askia Daoud, a civil war weakened the empire, which led the Saadi Dynasty of Marocco to begin an invasion, under the eunuch Judar Pasha. In 1591, at the Battle of Tondibi, the vastly numbered Songhai army, was stomped to death by cattle that was triggered by Saadi's gunpowder weapons.