The Kingdom of the Isles comprised the Hebrides, the islands of the Firth of Clyde and the Isle of Man from the 9th to the 13th centuries AD. The islands were known to the Norse as the Suðreyjar, or "Southern Isles" as distinct from the Norðreyjar or Northern Isles of Orkney and Shetland. The historical record is not complete and the Kingdom was not a continuous event throughout the entire period. The islands concerned are sometimes referred to as the Kingdom of Mann and the Isles during this period, although only some of the later rulers claimed that title. At times the rulers were independent of external control although for much of the period they had overlords in Norway, Ireland, England, Scotland or Orkney. At times there also appear to have been competing claims for all or parts of the territory. The islands involved have a total land area of over 8,300 square kilometres (3,205 sq mi) and extend for more than 500 kilometres (310 mi) from north to south.
Viking influence in the area commenced in the late 8th century, and whilst there is no doubt that the Uí Ímair dynasty played a prominent role in this early period, the records for the dates and details of the rulers are speculative until the late 10th century. Hostility between the Kings of the Isles and the rulers of Ireland, and intervention by the crown of Norway (either directly or through their vassal the Earl of Orkney) were recurring themes.