Meaning the "sons of the abbot", the MacNabs are said to have been descended from the younger son of King Kenneth I, who became lay Abbot of Glendochart, a religious house founded by St Fillan. The MacNabs opposed Robert the Bruce over the murder of John 'Red' Comyn in 1306, defeating Bruce at Strathfillan (1306), but then being defeated by him at the Pass of Brander (1308) and Bannockburn (1314).
Macnab clan territory lay in the Central Highlands, stretching from Tyndrum to Killin, but particularly Strathfillan, Glen Dochart and along the south shore of Loch Tay. The first chiefs lived at Innishewan then Bovain, later establishing a stronghold at Eilean Ran Castle at the mouth of the River Dochart but this was burned by Cromwell's troops in 1654. Their family burial ground was located nearby on the island of Inchbuie at Killin.
By the 18th century the clan chief was deeply in debt. The 16th Chief, Francis Macnab (1734 - 1816) lived extravagantly and, in 1828, his nephew and heir, Archibald Macnab (1777 - 1860), sold the lands to John Campbell, the Marquis of Breadalbane (1762 - 1834), and emigrated to Canada with a large number of his clansmen, settling along the Ottawa River Valley in Ontario.
In 1949, Archibald Corrie Macnab, the 22nd Chief, bought back Kinnell House and 2834 ha (7000 acres) of land from the Breadalbane Estate, although this was all sold once again to meet death duties in 1978. However, the clan retain Inchbuie and their ancient burial ground in perpetual trust.
Septs of the clan include Abbott, Dewar and Gilfillan.