Flann Sinna (died 916), also called Flann mac Maíl Sechnaill, High King of Ireland
A list of synchronisms, that is a series of known, datable events used to align Irish lists of kings to Scottish ones, was attributed Irish writer called Flann Mainistrech (Flann of Monasterboice) (d. 1056) in the eleventh century and provides another list of kings.
Eoin MacNeill considered Flann the first of the synthetic historians; this synthesis of biblical history and foreign world chronicles with Irish annals, myths and genealogical records was to be much emulated by subsequent writers.
Cormac mac Cuilennáin of the Eóganachta of Cashel, King of Munster, with his "evil genius" and later successor Flaithbertach mac Inmainén by his side, raided Connaught and Leinster in retaliation and, according to some annals, defeated Flann.