Sigurd Eysteinsson

According to the sagas, after the Battle of Hafrsfjord unified the Norwegian kingdom in or after 872, the Orkney and Shetland islands became a refuge for exiled Vikings, who raided their former homeland.

[3][4] The Historia Norwegiæ, written around the same time as the sagas but from a different source, corroborates the conquest of the islands by Rognvald's family, but omits any details.

[3] In league with Thorstein the Red, Sigurd expanded his domains to the Scottish mainland, and conquered Caithness and Sutherland at least as far south as Ekkjalsbakka, which some sources say was in Moray, but was much more likely to be farther north somewhere along the banks of the river Oykel.

[1] According to the Orkneyinga saga, towards the end of his reign, Sigurd challenged a native ruler, Máel Brigte the Buck-Toothed, to a 40-man-a-side battle.

He was buried in a tumulus known as Sigurd's Howe, or Sigurðar-haugr, from the Old Norse word haugr meaning mound or barrow.

The Orkney and Shetland islands lie to the north and east of the north-east coast of mainland Scotland. Caithness is the northernmost part of the mainland, with Moray further south. Caithness and Moray are divided by a firth, called Moray Firth. Just north of this, towards Caithness, lies another firth, Dornoch Firth, into which flows the river Oykel. Sigurd's Howe lies on the north bank of Dornoch Firth.
Map of north-eastern Scotland showing Orkney , Shetland , Caithness and Moray . At his death, Sigurd Eysteinsson controlled the area north of the river Oykel . The probable site of his burial mound, Sigurd's Howe, is shown.