From Ulster Ancestry A Sample of Irish Family Names http://www.ulsterancestry.com/irish-surnames.html JOHNSTON Origins in Ulster :Scottish Plantation One ofMessage 1 of 1 , Dec 16 1:46 AMView Source
From Ulster Ancestry
A Sample of Irish Family Names
Origins in Ulster :Scottish Plantation
One of the fours most common names in Fermanagh in 1700
The exact origins of this family are complicated when one takes into account the large numbers of both Irish and Scottish septs who share the names Johnston and Johnson.
However the Fermanagh South Tyrone Johnstons were of the Scottish border reiver family of that name.
In Scotland the Johnston name also has a number of origins. The city of Perth for instance was often called St Johnston and families took their name from that. Another was the lands of Jonystoun in East Lothian .
By far the largest and most important of these families were the Johnstons of Annandale in Dumfriesshire ,one of the great riding clans of the Scottish Borders. It is this family,scattered by James VI who are the source of most of the “true” Ulster Johnstons. Their ferocity (they were known as “The gentle Johnstons) made it possible for them together with their former fellow border reivers neighbours the Elliotts and the Armstrongs, to survive the 1641 rebellion which drove out other more faint hearted families.