Recent research has found that the Vikings had a greater genetic influence upon the Irish than previously thought.
Researchers at Trinity College Dublin believe that Viking and Norman invasions of Ireland may have made a more striking impression on the DNA breakup of the country than previously thought.
In January 2018 they also discovered 23 new genetic clusters in Ireland not previously identified, leading to the belief that we may have far more Viking and Norman ancestry than previously evidenced.
The Gallowglass were a powerful tribe of Gaelic speaking Vikings originally, from Norway who established themselves on the Western fringes of NW Britain, Isle of Mann and Eastern Ireland. There were also many Danish Vikings in Ireland and they eventually had a big battle during the 10th century for control of Ireland. The Danes won and the Gaelic speaking Norweagians fled to mainland Britain settling in SW Scotland and NW England.
The Norman invasion of Ireland resulted in the native Irish abondoning their Celtic Christianity for Roman Catholicism.
So I wonder how many of the native Irish reverted back to paganism after the Viking invasions? Here is an interesting archaeologic discovery:
It was found near Dublin and is called Thor’s Wood, which maybe a sacred grove. Sacred groves were important to the Celtic druids and also to Norse pagan religious practice and were normally referred to as lundr in Old Norse. These sites appear to have been relatively common and were often incorporated in later Scandinavian place-names. For example Þórs lundr (Thor’s Grove) is a common place-name in Denmark.