The kings of Osraige (alternately spelled Osraighe and Anglicised as Ossory) reigned over the medieval Irish kingdom of Osraige from the first or second century AD until the late twelfth century. Osraige was a semi-provincial kingdom in south-east Ireland which disappeared following the Norman Invasion of Ireland. A number of important royal Ossorian genealogies are preserved, particularly MS Rawlinson B502, which traces the medieval Mac Giolla Phádraig dynasty back through Óengus Osrithe, who supposedly flourished in the first or second century.[1][2] and one in the Book of Leinster (also known as "Lebor na Nuachongbála").[3][4] Recent analysis of ninth and tenth century regnal succession in Osraige has suggested that in peaceful times, kingship passed primarily from eldest to youngest brother, before crossing generations and passing to sons and nephews.[5]