The Fremen are the inhabitants of Arrakis, also known as Dune, the desert planet that is the sole source of the spice Melange in the known universe. The Fremen came to Dune thousands of years earlier as a religious sect in retreat; over time, surviving the incredibly harsh conditions of Dune bred them into the ultimate example of humans in extremis: a people bred purely to survive. Their language is based on Arabic, suggesting that they are descended from the Arabs of the forgotten planet Earth.
The Fremen are organized into sietches. Each sietch has a naib, whose word is law unless someone is willing to challenge him for leadership. The Fremen practice polygamy, apparently as a means of pinpointing male infertility. Each sietch has a sayyadina, a wise woman who is a native equivalent of a Bene Gesserit Reverend Mother.
The Fremen system of justice always relies ultimately on trial by combat. The naib of the tribe is someone who killed the previous naib in single combat. Anyone may challenge another in a duel to the death over matters of etiquette, law, or honour; the winner of the duel claims the wife, children, and possessions of the loser, as well as the right of the circumstances leading to the duel.Customs