to Sullivan. History Legendary genealogy According to the genealogy recorded in the 17th-century Leabhar na nGenealach, the O'Sullivan clan claimed descent from the Eóganachta dynasty of the Kings of Munster (and via them, ultimately, from Milesius, Fénius Farsaid and Adam). The legendary founder of the clan, Suilebhan mac Maolura, is recorded as born in 862 as a descendant from the line of the kings of Munster, of the Eóganachta dynasty, eight generations after Fíngen mac Áedo Duib (d. 618). Medieval period Following the Norman invasion of Ireland in 1169–71, Norman incursions into Munster were made in the 1180s. The O'Sullivan clan was forced from their original homeland in County Tipperary by the Normans in 1193. Dunlong son of Giolla Mochoda in 1196 from Tipperary to County Kerry. They divided into several branches and the two main ones are: O'Sullivan Mór (Mór indicating larger or greater) in south Kerry, and O'Sullivan Beare in the Beara Peninsula, West Cork and South Kerry The cadet branch of the O'Sullivan Mór dynasty is McGillycuddy of the Reeks (Mac Giolla Mochuda). Of the O'Sullivans Beare the cadet branch was the sept Mac Fineen Duff (Mac Fíghin Dúibh), now thought to be defunct. The "Beare" suffix came from the Beara peninsula that was named for the Spanish princess Bera, the wife of the first King of Munster. They continued to be harassed by the Normans and so allied themselves with the McCarthys and the O'Donoghues. The three clans defeated the Normans in 1261 at the battle of Caisglin near Kilgarvan, just north of Kenmare. They were again victorious the following year. These two battles settled the boundaries between the Normans of north Kerry (the FitzGeralds) and the three Gaelic families of south Kerry and west Cork. Early modern period The O'Sullivan Beare clan was further divided in 1592. When Dónal O'Sullivan, the chieftain, was slain in 1563 his son of the same name was but a child two years of age. The Irish laws of Tanistry required that the title of chieftain be passed on to the most capable of the dead chief's family. As a result, the clan decided that Owen, one of the brothers of the dead chief, would take over control of the clan and become Lord of Beare and Bantry. Owen acknowledged the English crown and was knighted by Queen Elizabeth. In 1587 Dónal, now twenty-six years old, decided to claim leadership