It is location of the Indian Army Special Forces Training School. It was the capital of the former Sirmur princely state.
Nahan is situated on a hill top in the Shiwalik Hills, overlooking green hills. Traditionally, saints and princes are linked with the origin of Nahan. The city was founded as in 1621 by Raja Karam Prakash. Another version recalls a saint who lived with a companion named Nahar on the site where the Nahan palace now stands. "Nahar" means 'don't kill' and the town probably takes its name from an incident when a king was trying to kill a lion and the saint said Nahar, that is 'do not kill it'.
The name of the saint was Baba Banwari Das. Another version is that Nahar means Lion in Sanskrit. At the place where Nahan is, Lions were there so it was named Nahar and latter called Nahan, which is distortion of Nahar