What is a fictional place where people have extremely long life span called?

A fictional place known for its inhabitants having extremely long lifespans is the mythical land of Shangri-La. Often depicted as a hidden paradise in literature, particularly in James Hilton's novel "Lost Horizon," it is said to be a utopia where people live in harmony and enjoy extended youth and longevity. Other examples include the "Land of the Immortals" in various Asian mythologies, where beings are granted eternal life.