way for a new Uí Cheinnselaig dominance in the region. Despite the defeat at Clontarf, Sigtrygg remained ruler of Dublin until 1036. High kings with opposition (1022 onwards) (Duncan) Donnchad mac Brian styled himself as 'King of Ireland' after the death of Máel Sechnaill, but failed to gain recognition as such. A glossing of Baile In Scáil lists Flaitbertach Ua Néill as high king, but he proved unable even to control the north of Ireland. Neither was anyone else able to make a recognised claim for kingship over all of Ireland: according to Byrne, "what distinguished the great interregnum of 1022–72 from other periods in Irish history is that it was recognised as such by contemporary observers". Flann Mainistrech had written Ríg Themra tóebaige iar tain, a regnal poem on the Christian (Uí Néill) kings of Tara some time between 1014 and 1022. When he wrote in 1056 he evidently did not know any high king of Ireland, and instead lists a number of kings of the day: (Duncan) Conchobar, Áed, Garbith, Diarmait, Donnchad (Duncan) and two Nialls. According to Byrne, these are Conchobar Ua Maíl Schechnaill of Mide, Áed Ua Conchobair of Connacht, Garbíth Ua Cathassaig of Brega, Diarmait mac Maíl na mBó of Leinster, Donnchad (Duncan) Mac Briain of Munster, Niall mac Máel Sechnaill of Ailech and Niall mac Eochada of Ulaid. The term rí Érenn co fressarba ("High kings with opposition") was used from the 12th century. According to Byrne, "it could be argued that the 'high kings with opposition' met with opposition precisely because they tried to become kings of Ireland in a real sense. They were not less successful than their predecessors, but only seemed so in the light of the teaching of the schools". Following a similar line of reasoning, Byrne suggests that the focus from historians on the decline of the Uí Néill in the 11th century may be a "tribute to the success of their own propaganda". After Brian, the previous Uí Néill monopoly of high kingship as described in poems and chronicles was anyway broken for good. The Cenél nEógain suffered from internal factions, and this allowed the Ulaid, under Niall mac Eochada, to expand their influence. Niall and Diarmait mac Maíl na mBó became allies, and effectively controlled the whole east coast of Ireland. This alliance helped to make it possible for Diarmait to take direct control of Dublin in