How did the name Scot originate?

The name Scot to refer to the people who live in the north of the British Isles comes from the Latinised form of the name of an Irish tribe, the Scotti, who moved to the south-west of Scotland in the 6th century to form the Kingdom of Dalriada. When this was unified with Pictland by King Kenneth I MacAlpin, it became known as Scotland

A popular myth as to the origin of the Scotii's name is that a leader of the Scotii traveled south to Egypt, married an Egyptian princess called Scotia, but that all sounds rather fairy story to me