The MacDonalds of Keppoch are descended from Alistair Carrach MacDonald who was a younger son of Good John of Islay, Lord of the Isles, 6th chief of Clan Donald and his second wife Margaret Stewart, daughter of King Robert II of Scotland. John of Islay, Lord of the Isles, apportioned his estates between the children of his two marriages in accordance with the marriage settlement of his father-in-law Robert II of Scotland and the Lordship of Lochaber was given to Alistair Carrach MacDonald who was the third and youngest son from his second marriage.
The MacDonalds of Keppoch trace their lineage back to Alistair Carrach MacDonald, a younger son of Good John of Islay, 6th chief of Clan Donald, and his wife Margaret Stewart, daughter of King Robert II of Scotland.  John of Islay, Lord of the Isles, distributed his lands among his children according to the agreement made by his father-in-law, Robert II of Scotland, and Lochaber was given to Alistair Carrach MacDonald, who was the youngest son from his second marriage.