In the early 12th century, Somerled, a Norse-Gael of uncertain origin, became owner of Arisaig and the surrounding region. No reliable record explains how this happened, but by some point in the 1140s, David I of Scotland's control of the region had been eroded. In the middle of that century, Somerled launched a coup in the Kingdom of the Isles, which led to it joining his other possessions as a single state. On Somerled's death Norwegian authority was restored, but in practice it remained divided; the part containing Arisaig was known as "Garmoran" and ruled by the MacRory, a faction among Somerled's heirs.