Before King Edgar’s death in 1107, he bequeathed the kingdom of Scotland to his younger brother Alexander as King and his youngest brother David for southern Lothian and Strathclyde (Cumbria).

Alexander (born about 1077) was known by the sobriquet ‘the Fierce’ both for his suppression of rebellions in Moray and the Mearns and his efforts to defend the independence of the Church in Scotland from England. Alexander’s sister Edith (known as Queen Maud in England) was married to King Henry I of England and Alexander married his brother-in-law’s illegitimate daughter Sibylla. His reign is remembered for his encouragement of monastic orders. Augustinian priories were founded at Scone, Inchcolm and planned for Dunkeld and Saint Andrews.

In 1115, Earl Madach, son of Melmare, Malcolm Canmore’s youngest brother was given the earldom of Atholl. This Earl witnessed the granting of a Foundation Charter at Scone by his first cousin Alexander I. Earl Madach married Margaret, the daughter of Haakon, Earl of Orkney and they had a son, Harold who succeeded his father as the Earl of Orkney in 1139.

On Alexander’s death at Stirling in April 1124, without legitimate issue, he was buried at Dunfermline Abbey. His younger brother David ascended the throne at the age of about forty-four as King David I.

References:
Cowan, Samuel, "Three Celtic Earldoms", Edinburgh, 1909, pp. 14-15.
Bingham, Caroline, "Kings and Queens of Scotland", New York, 1976, pp. 20-21,150.
Paton, Sir Noel, "The Descendants of Conan of Glenerochie", privately printed, 1873, p. 3.