Flatbread was already known in Ancient Egypt and Sumer[when?]. In ancient Mesopotamia (modern day Iraq) the Sumerians discovered that edible grains could be mashed into a paste and then baked/hardened into a flatbread.
The term unleavened bread can also refer to breads which are not prepared with leavening agents. These flatbreads hold special religious significance to adherents of Judaism and Christianity. Jews consume unleavened breads such as matzo during Passover.
Canon Law of the Latin Rite of the Roman Catholic Church mandates the use of unleavened bread for the Host, and unleavened wafers for the communion of the faithful. The more liturgical Protestant churches tend to follow the Latin Catholic practice, whereas others use either unleavened wafers or ordinary bread, depending on the traditions of their particular denomination or local usage.