Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Ruarc mac Brain (died 862) was the fourth of ten Kings of Leinster to be inaugurated and based on Lyons Hill, Ardclough, County Kildare, a member of the Uí Dúnchada, one of three septs of the Uí Dúnlainge dynasty which rotated the kingship of Leinster between 750-1050, significant in County Kildare History. One of two sons of Bran mac Fáeláin to be counted as king, the succession of kings in Leinster is difficult to follow in his time. The king lists have Ruarc succeed his father, and be followed by Lorcán mac Cellaig, and then Túathal mac Máele-Brigte and lastly Muirecán mac Diarmata, who died the year after Ruarc. In 843 the Annals of Ulster record that Artacán mac Domnaill was "deceitfully killed" by Ruarc mac Brain, but no further identification or titles are give. Likewise in 846, when he fought alongside Máel Sechnaill mac Máele Ruanaid and was defeated by Tigernach mac Fócartai no titles are given. His obituary in the Annals of Ulster in 862 calls him only "king of Uí Dúnlainge".