Complex sentence: He manages to save his leader and dies in his granddaughter's hands making her promise that she will teach their leader everything and make him the Ruler again, and help abolish the slavery in their country.
Split into simpler sentences: He manages to save his leader and dies in his granddaughter's arms. At his death, he makes her promise that she will teach their leader everything and make him the ruler again, and help abolish slavery in their country.