Tomrair mac Ailchi, or Thormod/Thorir Helgason, was the Viking

Viking

The term Viking is customarily used to refer to the Norse explorers, warriors, merchants, and pirates who raided, traded, explored and settled in wide areas of Europe, Asia and the North Atlantic islands from the late 8th to the mid-11th century.These Norsemen used their famed longships to...

 jarl

Earl

An earl is a member of the nobility. The title is Anglo-Saxon, akin to the Scandinavian form jarl, and meant "chieftain", particularly a chieftain set to rule a territory in a king's stead. In Scandinavia, it became obsolete in the Middle Ages and was replaced with duke...

 and prince

Prince

Prince is a general term for a ruler, monarch or member of a monarch's or former monarch's family, and is a hereditary title in the nobility of some European states. The feminine equivalent is a princess...

 who reestablished the preexisting small Norse

Norsemen

Norsemen is used to refer to the group of people as a whole who spoke what is now called the Old Norse language belonging to the North Germanic branch of Indo-European languages, especially Norwegian, Icelandic, Faroese, Swedish and Danish in their earlier forms.The meaning of Norseman was "people...

 base or settlement at Limerick

Limerick

Limerick is the third largest city in the Republic of Ireland, and the principal city of County Limerick and Ireland's Mid-West Region. It is the fifth most populous city in all of Ireland. When taking the extra-municipal suburbs into account, Limerick is the third largest conurbation in the...

 as a powerful kingdom in 922, and overnight, when he is recorded arriving there with a huge fleet from an unknown place of departure. His ancestry is uncertain but he evidently did not belong to the Uí Ímair

Uí Ímair

The Uí Ímair , or Dynasty of Ivar, were an enormous royal and imperial Norse dynasty who ruled Northern England, the Irish Sea region and Kingdom of Dublin, and the western coast of Scotland, including the Hebrides, from the mid 9th century, losing control of the first in the mid 10th, but the rest...

 dynasty who only a few years before had reestablished themselves in the Kingdom of Dublin, of which Tomrair, the first King of Limerick

History of Limerick

The history of Limerick , stretches back to its establishment by the Vikings as a walled city on King's Island in 812, and its charter in 1197....

, would immediately make himself the chief rival.