In the 9th century, much of Scotland wiz gettin' a doin' from the Scandinavians (unlike today, when we regularly give them a doin' at the footie .... Ha, ya big foreign numpties).

Parts of Scotland (principally Hebrides, Caithness, Orkney, Galloway, Moray, Banff, and Shetland) became a part of Norway and the Norse language displaced Gaelic.

Murchadh is the Norse word for sea warrior.

Famous Murdoch's include:

William Murdoch Officer who died on the Titanic and who's memory was seriously debased by the film Titanic, made by Fox.
Rupert Murdoch Seriously wealthy Australian who's companies include Fox, who made the film Titanic.
PC Murdoch Overweight policeman and a fundamental part of The Sunday Post's Oor Wullie cartoon.
William Murdoch Inventor of gas lighting