How the Welsh caught the Yellow Plague

Abstract

The ‘Yellow Plague’ (pestis flava, buidechair, ball felen, etc.) is a term used by Irish and Welsh authors working in the tenth century and later to describe several epidemics of the sixth and seventh centuries. This paper examines one particular set of stories about this illness found in Welsh sources written between 1100 and 1223, in which the Yellow Plague is responsible for a mass migration from Wales to Brittany. This legend, I argue, was likely created at Llancarfan in the late eleventh century from various older sources, including annals and saints’ Lives from Ireland and Brittany; I also provide an account of how this legend may have been transmitted to other Welsh centers, and suggest connections to other contemporary works of pseudo-history, such as Geoffrey of Monmouth’s De gestis Britonum.