A Mohican - called a Mohawk in the US - is "a hairstyle with the head shaved except for a central strip of hair from the forehead to the back of the neck, typically made to stand erect", in the words of the OED.

Erect! Snigger.

Anyway, the Mohicans and the Mohawks were Native American tribes, originally from the area which is now upstate New York. However, neither of the tribes sported the hairdo which now bears their name. It was popularised by film and TV adaptations of James Fenimore Cooper's 1826 novel "The Last of the Mohicans" - but it was the Huron Indians who actually had the haircut.