The city of Dublin, having started life in the ninth century as a Viking encampment, had been in evolution for over 300 years by the time of its conquest by the English on 21 September 1170. For much of the tenth century its rulers also ruled the city of York, and it was minting its own coins, modelled on the Anglo-Saxon equivalent, by that century's end. In the early eleventh century there is some evidence of links with the Anglo-Danish empire, then a close if doomed partnership with the house of Wessex. The only visible effects of the coming of the Anglo-Norman and Angevin ages, until the late 1160s, were ecclesiastical ties, particularly with Canterbury, and an expansion in the market for Dublin's traders. The latter and their fellow citizens could in 1121 write collectively of themselves as omnes burgenses Dublinae civitatis. We know that they met regularly in an assembly, which was presumably not unlike the Folkmoot of London, and which the Dubliners called their Thingmoot (þingmót). Even if we had no documentary evidence for the Thingmoot, we should have to extrapolate its existence from the abundant surviving proof – archaeological, ecclesiastical, diplomatic, and so forth – of collective activity.
But in 1170 Dublin was conquered. A battle took place between its hereditary Hiberno-Norse ‘king’, Ascall Mac Turcaill, commanding a substantial military and naval force, and Richard de Clare (‘Strongbow’), sometime earl of Pembroke and Strigoil. The latter considered himself heir to the kingdom of Leinster because he had recently married the daughter of its king, Diarmait Mac Murchada, and, like most of his contemporaries, viewed Dublin as implicitly the province’s capital city.