The Armstrong presence in the Liddesdale area of the Border dates, at least, from the middle 1300's.  Before then, they could be found in Cumberland, but in 1376, the first of that name in Scotland, Alexander Armgstrand, was documented in Mangerton, in Liddesdale. 

It has been stated that the original name was Fairbairn.  A powerfully built man of that name was asked to help the King to mount his horse.  The result was that he, with one arm, caught hold of His Majesty and lifted him into the saddle.  He was then dubbed Armstrong.  This prolific family soon rose to be one of the ruling clans, along with the Elliots, of the Liddesdale area of the Border.

The Armstrongs of Mangerton, the chiefly house of this family, kept their lands until 1610, when Archibald Armstrong of Mangerton was "put to the horn" as a rebel.  Soon afterwards, the rest of the Armstrong lands passed to the Scotts.