This notable surname of early medieval Irish and Scottish origin, is an Anglicized form of the Old Gaelic "MacLachlainn", son of Lochlann, a male given name which ultimately derives from the Old Norse "Lochlann", a compound of the elements "loch", lake, fjord, and "lann", land. This personal name, originally taken to mean "stranger", was applied as a byname to Viking settlers, from the name used for Scandinavia, i.e. "Fjordland". The Irish sept of MacLochlainn or MacLoughlin was a senior branch of the northern Ui Neill (an ancient population group located in Counties Donegal, Derry and Tyrone), and their territory lay in Innishowen, Co. Donegal, where the name is chiefly found today. Up to the year 1241, when the MacLochlainn ascendancy in Ulster was finally ended at a battle of that date, the leading men of the sept are frequently mentioned in the Annals of Medieval History. The chief seat of the Scottish Maclacklan clan is in Cowal, Argyllshire, the lands of which were acquired by Gilleskel Maclachlan in 1292, and as early as 1314, we find their stronghold there referred to as "Castellachlan" or Castle Lachlan. Some MacLachlans were for centuries hereditary captains of Innischonnel to the Argylls. One Gillaspy Maclachlan was present at the parliament held at St. Andrew's on March 16th 1308. The first recorded spelling of the family name is shown to be that of Lochlainn MacLochlainn, which was dated 1068, in the "Annals of the Kingdom of Ireland", during the reign of High Kings of Ireland "with opposition", 1022 - 1166. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.