The People That Time Forgot is the second book in the Edgar Rice Burroughs Caspak trilogy along with The Land That Time Forgot and Out of Time's Abyss.
The People That Time Forgot is the sequel to The Land That Time Forgot and continues the lost world saga. Burroughs continues the revelation of his lost world's unique biological with a slow progress of evolution.

The People That Time Forgot begins with the organization of an expedition to rescue Bowen J. Tyler, Lys La Rue, and the other castaways marooned on the large Antarctic island of Caprona, whose tropical interior, known to its inhabitants as Caspak, is home to prehistoric fauna of various eras. Tyler's recovered manuscript detailing their ordeal is delivered to his family, and the relief effort is put together by Tom Billings, secretary of the Tyler shipbuilding business.

Edgar Rice Burroughs was an American author, best known for his creation of the jungle hero Tarzan, "Lost worlds" and the heroic Mars adventurer John Carter.