Bappir is a Sumerian term used to describe a twice-baked barley bread that was primarily used in ancient Mesopotamian beer brewing. Historical research done at Anchor Brewing Co. in 1989 (documented in Charlie Papazian's Home Brewer's Companion (ISBN 0-380-77287-6)) reconstructed a bread made from malted barley and barley flour with honey and water and baked until hard enough to store for long periods of time; the finished product was probably crumbled and mixed with water, malt and either dates or honey and allowed to ferment, producing a somewhat sweet brew. It seems to have been drunk with a straw in the manner that yerba mate is drunk now.
It is thought that bappir was seldom baked with the intent of being eaten; its storage qualities made it a good candidate for an emergency ration in times of scarcity, but its primary use seems to have been beer-making.
A modern homebrewing attempt at baking bappir (and the resultant brew) was done by the Maltose Falcons Home Brewing Society with a recipe of how to brew beer from bappir bread.