 The site of the monastery was given to Máel Ruain "in honour of God and St. Michael" by Cellach (d. 18 July, 771) of Ui Donnchada, grandson of a Leinster king, Donogh (d. 726).The monastery withstood an attack by Vikings in AD 811 and survived as a discrete entity to the time of the Anglo-Norman invasion of 1169.Subsequent to the turmoil of that period, Pope Alexander III issued a bull dated 20 April 1179, by which Tallaght, along with its subsidiary chapels of Killohan and St. Bride’s, was united to the Archdiocese of Dublin.