A son of Tadc in Túir (of the tower), Conchobar's father died in 956 as king of Connacht, but his sept of the Síol Muireadaigh were successfully opposed by Fergal ua Ruairc of the Uí Briúin of Bréifne, who reigned till 967.
It was his brother-in-law Domnall son of Congalach who slew Fergal grandson of Ruarc in 966, leaving the way clear for Conchobar to assume overkingship of Connacht, the new provincial ruler, however, was not to enjoy an untroubled reign.
Mac Shamhráin states: "It seems that the provincial kingship remained weak for the next twenty years, as dynasty from several different lines extended their sway over parts of Connacht.
However, through his son Cathal, who eventually emerged as provincial ruler, Conchobar became the ancestor of the royal line of Ua Conchobair (O'Connor), which provided most of the later kings of Connacht.
A brother of Conchobar's was Máel Ruanaid Mór mac Tadg, ancestor of the Kings of Moylurg and the families of Ua/Ó Maolruanaid (Mulrooney) and MacDiarmata (MacDermot).