The name Trehy originates almost exclusively from the south of Ireland in counties Limerick, Tipperary, Cork, and Kilkenny. A variant of the name, Trihy / Trihey is found mainly in the Waterford & Cork border areas. Other variants of the name, such as Trahy, Trahey, and Treahy exist in these counties also, but records suggest that these are more the result of registration & transcription errors rather than different names or family lines.
I have seen, for example, in many cases, a couple’s first child registered as a Trehy, and subsequent children registered as Trahey / Treahy. This is true also of many official records I have come across from all over the world. From my experience it is a fact that most Trahey / Treahy / Trehey lines around the world can be traced back to a Trehy in Ireland. Indeed all the Traheys in Newfoundland would appear to be descended from a Timothy Trehy whose father was born in Ireland.The main reasons for these variations can be attributed to;Lack of literacy on the parts of the individuals themslves.Incorrect recording of parish records by clergy.Incorrectly recorded names on ships manifests.Census takers and even family members incorrectly spelling names.Transcription errors. In many cases these name change have been carried down into later generations. Transcription, by its very nature, is highly prone to human error because of the varying quality and readability of source records. As a result of this Ancestry.com is dotted with corrections submitted by members, including many submitted by myself. In US census returns in particular I have found our name invariably spelt as Trichy, Trickey, Tryhy, to name but a few variations. This has made research much more complicated as all these variations have to be considered.