Charlemagne, Sojourner Truth and Genghis Khan are some illiterate historical figures. Their illiteracy was due to social and cultural circumstances.
Charlemagne, or Charles the Great, was King of the Franks and Roman Empire beginning in 771 A.D. As a youth, he was illiterate, as was most of the Frankish society and even the majority of the nobles. At the time, the educated clergy were the most literate.
Isabella Baumfree was an African-American slave in New York who escaped in 1826, became a Christian, changed her name to Sojourner Truth and dedicated herself to spreading evangelism. Despite her illiteracy, she was an effective proponent of women's rights and the abolition of slavery.
Genghis Khan was an illiterate Mongol leader. The Mongols were religious and moved in bands called "khan." Khan created a code of laws for the Mongol people and led them in land-conquering wars to establish a powerful empire.