The name Forbes is most probably a location name assumed from the lands of Forbes in Aberdeenshire, in possession of this family reputedly since the time of King William the Lion. While there are many legends surrounding the origins of this clan historians write the Forbes are descendents from Kings of the Picts and a reliable tradition tells that the "Braes o’ Forbes" were once uninhabitable because of bears living in the area. Oconachar, founder of the clan, killed the bears and claimed the land as "first occupier". The present chief still holds part of the Lordship of these Forbes lands. The first person on record was Duncan Forbes who in 1271–2 received a grant of lands from Alexander III of Scotland. Cited by William Forbes Skene the charter exists in the Forbes charter chest in tattered but quite legible condition.

The next mention is a John Forbes, whose name dates from a 1306 roll containing a list of demands by English and Scottish loyalists to Edward I of England for the forfeited lands of Scotsmen, the lands of John Forbes being demanded or requested by both a William Comyn and a Robert Chival. The next name may be that of his son, Christian, who received a grant of one-third of the lands of Skeith and Ardach by King Robert the Bruce in 1326, but doubt still remains he was a Forbes or of this family, even though in the charter he is named Christian Forbes.

The next name found in records is that of John Forbes dominus ejusdem or Lord of Forbes. He witnessed two charters of Thomas, Earl of Mar in 1358 and 1359 and in 1364 King David II of Scotland confirmed a charter for the lands of Edinbanchory and Craiglogy by Thomas, Earl of Mar granting them to John de Forbes. He was Sheriff of Aberdeen in 1374. In 1378 a charter was granted to John and his wife Margaret by the Bishop of Moray for the lands of Fynrossie on the loch of Spynie. At his death before 20 August 1387 he was described as "a gude man, wise, and mychty, and manly in his time."

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