The information in this article is from the fan game King's Quest ZZT and is therefore not canon.
Arba, the Centaur, is an inhabitant of the secret Centaur Village on the Island of Llewdor. He explained that the centaurs were always moving because the Ogres hunted their kind to eat their meat. Alexander promised to kill any ogres he came across, suggesting it would scare them the ogres away, and stop the attacks on their village. Arba was pleased, and allowed Alexander to sleep in the village inn.