John was the second son of Lachlan Bronneach Maclean and Fionnaghal, daughter of Sìol Tormoid[note 1] leader.
When John grew into an adult, he gained the sobriquet Garbh, meaning rough, in reference to his gigantic stature and great strength.
However, Clan Ranald refused to acknowledge the sale[1][note 5]; John Garbh consequently seized Allan MacDonald, and held him prisoner on Coll.
After 9 months, Allan was released, presumably having agreed to acknowledge a sale; following this, records describe Rùm (with Canna and Muck) as pertaining to John Garbh's descendants, rather than to Clan Ranald.
[2] This article incorporates text from A history of the clan Mac Lean from its first settlement at Duard Castle, in the Isle of Mull, to the present period: including a genealogical account of some of the principal families together with their heraldry, legends, superstitions, etc, by John Patterson MacLean, a publication from 1889, now in the public domain in the United States.