Run of Alt Clut

Rhun ab Arthgal was a ninth-century King of Strathclyde. He is the only known son of Arthgal ap Dyfnwal, King of Alt Clut. In 870, during the latter's reign, the fortress of Alt Clut was captured by Vikings, after which Arthgal and his family may have been amongst the mass of prisoners taken back to Ireland. Two years later Arthgal is recorded to have been slain at the behest of Causantín mac Cináeda, King of the Picts. The circumstances surrounding this regicide are unknown. The fact that Rhun seems to have been Causantín's brother-in-law could account for Causantín's interference in the kingship of Alt Clut.