Originally Posted by Matthew A. C. Newsome via http://albanach.org/leine.html
Although[/url] it is difficult to come to too many conclusions about Irish dress from this period, it seems to be the consensus of the scholars that the léine costume was that of the aristocracy, or at least those with some authority, in the 10th century and before. In this time, we do find another form of dress, however—that of the tight fitting trews, worn with a jacket. We never see the léine and trews being worn together, though (at least not at this early period). One theory put forth that has met with some acceptance is that the trews, which are similar to other northern European garments, belonged to the native Irish. When the conquering Gaels came in sometime before 300 BC, they brought with them their looser fitting clothing, the léine or tunic. These people conquered and ruled over the indigenous people much the same way the Normans ruled over the Anglo-Saxons. Even though the conquered race eventually spoke the Gaelic language and called themselves by the same name, it was the upper class who wore the léine and the common man retained the native garb.