Explanation:

 The name Kullu derives from the word "Kulant Peeth", meaning "end of the habitable world". As per legends, during the Great Flood, Manu visited this valley, but was unable to cross the Rohtang pass. He named the last settlement he found as Kulant Peeth, and chose to settle and meditate in what has now become the town of Manali (Manu's Place). The name further devolved into "Kulut", as the kingdom was known for a long time; before finally being known by the current name of Kullu .