Diarmait mac Cerbaill

Diarmait mac Cerbaill (died c. 565) was King of Tara or High King of Ireland. According to traditions, he was the last High King to follow the pagan rituals of inauguration, the ban-feis or marriage to goddess of the land.

While many later stories were attached to Diarmait, he was a historical ruler and his descendants were of great significance in Medieval Ireland. He is not to be confused with the later Diarmait mac Cerbaill (King of Osraige), son of king Cerball mac Dúnlainge.

It is believed that the earliest of the Irish annals which came to make up the lost Chronicle of Ireland were kept as a contemporary record from no later than the middle of the 7th century, and may be rather older as it has been argued that many late 6th century entries have the appearance of contemporary recording. There is general agreement that the annals are largely based, in their earliest contemporary records, on a chronicle kept at the monastery on Iona, and that the recording moved to somewhere in the midlands of Ireland only around 740. Although it is thus possible that the records of Diarmait's times in the annals are nearly contemporary, the later history of the annals is complex and much debated, so that it is uncertain to what extent surviving late annals such as the Annals of Ulster and Annals of Tigernach faithfully reproduce the earlier records. The sparsity of the annalistic record, its laconic manner of reporting, and the complex history behind the surviving records mean that there is little which can be stated with certainty concerning Diarmait mac Cerbaill's life and times.

As a significant ancestral figure, whose purported descendants included many leading kings from the 7th to early 11th centuries, Diarmait appears in many genealogical collections and related materials. While it was once supposed that such materials were to be relied upon, many modern historians doubt whether genealogies can be taken as evidence for anything more than political aspirations and beliefs in the milieu in which they were compiled. Reinforcing this view, Diarmait's recorded ancestry and family ties are believed to have been the subject of politically motivated changes in the centuries following his death.

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