A flatbread is a simple bread made from flattened dough. Many flatbreads are unleavened—made without yeast or sourdough culture. They can range from one millimeter to a few centimeters thick. Flatbread was already known in Ancient Egypt and Sumer.
The term unleavened breads can also refer to breads which are not prepared with leavening agents. These flatbreads holds special religious significance to adherents of Judaism and Christianity. Jews consume unleavened breads such as Matzo during Passover. They are also used in the Western Christan liturgy when Christians celebrate the Eucharist.
In 2000 Edward de Bono advised a U.K Foreign Office committee that the Arab-Israeli conflict might be due, in part, to low levels of zinc found in people who eat unleavened bread, a known side-effect of which is aggression. He suggested shipping out jars of Marmite to compensate.