Báetán mac Ninnedo laughed Ard Érenn of 572 with 586.

Baétan would be the son of Ninnid mac Dui mac Fergus Cennfhota mac Conall Gulban the founder of the Cenél Conaill.

The Yearly of Ulster, Annals of Tigernach raise its murder in 586 and specify that it was killed by Cuiméne mac Colman Bec and Cuiméne mac Libren mac Illand mac Cerbaill at the instigation of Colman Bec (death in 587) mac Diarmait mac Cerbaill.

On the other hand the Annales of Ulster and the Annales of the four Masters agree to credit it with a reign of only one year what is in contradiction at the same time with:

• the Annales of Tigernach which mention its accession with the throne of Tara in 573.
• the chronology interns Annals of Ulster for the reigns of Ard laughed Érenn since Diarmait mac Cerbaill.
• the chronology of the reign of its successor Áed mac Ainmerech died in 598 to which them Annales of the four Masters allot a 27 years reign but which became laughed Ard Érenn in 586.

This one 28 years total duration period corresponds in fact to the duration of the cumulated reigns of both laughed Ard Érenn; Baétan mac Ninnedo and Áed mac Ainmerech. Duration of the reign of Báetán mac Ninnedo having to be established at approximately 13/14 years.