What language did the Benin learn to write and read?

The Benin Empire refers to the Edo people of Africa, rather than the modern state of Benin - also in Africa, though not related to the Edo civilisation. The Empire lasted from 1440 to 1897 when it was conquered by the British Empire. The Benin people traded with Europeans from the 15th Century when they came into contact with Portuguese explorers. This trade continued for hundreds of years and a lot of what we know comes from European accounts. They traded tropical products such as ivory, peppers and palm oil which were rare in Europe.