The Scottish Highlands were in the northern area of Scotland.
Jamie McCrimmon was a Highland Scot from the mid-18th century who travelled with the Second Doctor, Polly Wright, Ben Jackson, Victoria Waterfield and Zoe Heriot. He also had a couple of adventures with Brigadier Lethbridge-Stewart (TV: The Web of Fear, TV: The Invasion) as well as the Sixth Doctor and Peri Brown. (TV: The Two Doctors, COMIC: The World Shapers) Bernice Summerfield remembered the Seventh Doctor as having a Highlands accent as opposed to the Twelfth Doctor, who had more of a Glaswegian accent. (PROSE: Big Bang Generation)
Highland regiments were part of the British Army in World War I. The Highlanders gained a reputation as fierce soldiers in the conflict. The Germans called them "the devils in skirts" and "the ladies from hell." (AUDIO: The Mouthless Dead) Highland regiments were also a part of World War II. (AUDIO: Resistance, The Forsaken)