The zone where unsalted bread is eaten in Central Italy.

from the Introduction
According to Perugians, their hatred of the pope has been so intense and so constant since 1540 that it even manifests itself in Perugian cuisine. The traditional (and indeed still best-selling) bread in Perugia is locally known as pane sciapo, supposedly a result of the popular protest against the higher taxes on salt imposed on the Perugians in 1540 by Pope Paul III, the reason for the war that ended Perugia’s proud tradition of relative freedom from papal interference in municipal affairs. Perugians take pride in explaining the history of their bread and their fight with the pope to the foreigners who flock to Perugia to study. There are, however, several other popular explanations (not necessarily limited to Perugia) for this lack of salt, which yields bread quite different from most of the rest of the peninsula’s culinary traditions. This paper will examine these explanations which are often used in central Italy in an attempt to see if they coincide with indications of historical veracity from geographical, literary, and historical sources.