According to legend, Scáthach, or Sgathach, lived some time in the centuries either side of 200BC. She was a mythical warrior queen whose fortress was on the Isle of Skye. The wider picture in Scotland at the time is set out in our Historical Timeline.
Scáthach, whose name in Gaelic means "Shadowy" appears in the Red Branch Cycle, a collection of medieval Irish heroic legends and sagas that forms one of the four great cycles of Irish mythology. By some accounts she was the daughter of the King of Scythia which encompassed parts of Eastern Europe and Asia. She was a legendary warrior woman and martial arts teacher whose fortress Dún Scáith (Castle of Shadows) was on the Isle of Skye. The ruins of Dun Sgathaich near Tarskavaig, which date back to the 1300s, are said to stand on the site of Dún Scáith. Scáthach was reputed to train only those young warriors already skilled and brave enough to penetrate the many defences of her fortress and gain access.
Scáthach appears in the Irish legends because one of those who successfully came to her for training was the legendary Ulster hero Cúchulainn, after whom, it is said, the Cuillin on Skye are named. The back-story is that Cúchulainn had fallen in love with Emer, but her father, Forgall, only agreed to their marriage on the condition that Cúchulainn first completed his training as a warrior. Cúchulainn and his friend Ferdiad duly travelled to Skye and gained access to Dún Scáith, where Scáthach turned them into fully fledged warriors. She also gave Cúchulainn his deadly barbed spear, the Gáe Bulg.
As part of his training Cúchulainn helped Scáthach overcome a neighbouring female chieftain, Aífe or Aoife (who by some accounts was also Scáthach's sister), and forced her to make peace, in the process fathering a son by Aífe. Cúchulainn also ended up sleeping with Scáthach's daughter Uathach, whose husband Cochar Croibhe he then killed in a duel. On completion of his training, Scáthach also slept with Cúchulainn.
By some accounts Scáthach was also a formidable magician with the gift of prophecy. She also, again by some accounts, became the Celtic goddess of the dead, ensuring the passage of those killed in battle to Tír na nÓg, the Land of Eternal Youth and the most popular of the Otherworlds in Celtic mythology.