The Lost Tribe are an (Indigenous) ethnic group that live in (almost) complete isolation from the outside world, oblivious to the existence of global civilization, modern technology, and other contemporary concepts. In realistic stories, they may live in a remote Wild Wilderness that is inaccessible to most outsiders. In a fantasy story, they may live in a Lost World. In science fiction, they may be inhabitants of another planet.
However, their way of life may be changed after being contacted by foreign people and modern technologies and cultural practices from the outside world.
Also related to Hollywood Natives, Noble Savage, The Savage Indian, Last of His Kind, Contemporary Caveman, Schizo Tech, and Hidden Elf Village. Not necessarily related to Wacky Wayside Tribe. See also the Lost Colony, which is related except the inhabitants are not Indigenous.
- Yu-Gi-Oh! has survivors of Atlantis.
- The eponymous kingdom in Indiana Jones and the Kingdom of the Crystal Skull is populated by natives who guard it from outsiders (and presumably maintain the Durable Deathtraps).
- The B-movie Mexican Blow has Indians from north of the Rio Grande who migrated to southern Mexico to escape the white man and speak English so they won't be tricked by the white man again. All the Indians are white, but the main character is a Mighty Whitey too.
- One band of villains in Yellow Hair and the Fortress of Gold is a lost tribe of Aztecs (or, at least, Mayincatecs).
- At Play in the Fields of the Lord has theories that the Niaruna are the Lost Tribes of Israel or a lost tribe of Sioux.
- Kushiel's Legacy has the main character of the first trilogy run into the Tribe of Dan, one of the Lost Tribes of Israel, guarding The Ark of the Covenant down around what in our world is Lake Victoria.
- Star Wars Legends
- In The Courtship of Princess Leia, we’re introduced to the Dathomiri, who descended from prisoners in a penal colony on the planet, including one female rogue Jedi who took power over the rest. Over time, her descendants became (all female) Force users, or the so-called "witches". Since then, they were cut off from the rest of the galaxy and developed on their own.
- Fate of the Jedi features a faction of the old Sith Empire known as the Lost Tribe of Sith, who descended from the survivors of a ship crash on the planet Kesh during the Great Hyperspace War over five thousand years before.
- Incandescence: The Splinterites, insectoid aliens who live in tunnels in a small meteor, make contact with other members of their species who live in similar meteors orbiting the same black hole. Eventually they develop interstellar travel and become the Aloof, a civilization that discourages members of other species from going near the center of the galaxy because it's too dangerous. But they failed to discover one rock, whose inhabitants lived for millions of years in total ignorance of the world outside their little world until they are discovered by Rakesh and Parantham.
- Island's End has the En-ge of the Andaman Islands, who used to live on a large island with a bunch of other tribes. An offshoot of the tribe that included Uido's grandparents moved to a smaller, more isolated island to escape modern influence, where they've been living in almost total isolation ever since. Uido travels by canoe back to the larger island with her sick brother so he can be treated in a hospital. While there, she learns that the original branch of the En-ge died out, meaning her people are the only ones left.
- In Small Gods, Fasta Benj is a member of an isolated tribe of marsh-dwelling nomads with no concept of fire, metal, or war, which might have stayed that way if Fasta Benj hadn't been fishing when his boat got caught up in the wake of a massive fleet. After his god made him promise not to wage war (which was explained to him as like Pacha Moj hitting his uncle in the head with a rock, but worse), he left with metal, knowledge of fire, and some confusion about why lots of people would want to hit Pacha Moj's uncle.
- The Goodies: In "The Lost Tribe of the Orinoco", the Goodies go in search of the eponymous lost tribe and find it in a most unexpected location.
- The titular lost tribe in the Stargate Atlantis episode "The Lost Tribe".
- The lost tribes of Israel are the Trope Namer. Either in The Bible or The Book of Mormon. Mormons believe that American Indians are descended from Jews (or more accurately, descended from Manassites who lived in Jerusalem. Europeans are mostly descended from Ephraim, so most people in the Americas are from Joseph).
- In some New Age beliefs, American Indians are aliens.
- Chrono Trigger has a lost tribe of Mystics, and survivors of the Kingdom Of Zeal.
- Chrono Cross has survivors of other timelines.
- Final Fantasy likes to use this trope:
- In the Marathon franchise, ten clans of S'pht were living on planet Lh'owon when it was conquered by the Pfhor, who then enslaved the S'pht. There was a legendary eleventh clan, the S'pht'Kr, who left Lh'owon prior to the Pfhor invasion. Late in the second game the S'pht'Kr are found and return to Lh'owon to liberate their brethren.
- The Legend of Dragoon has the last surviving dragons.
- Uzo and Muzo are the last survivors of the Mt. Gokuho clan in the game Kingdom of Paradise. Shinbu makes them lost for good.
- The Tomb Raider 2013 Reboot Trilogy features three different tribes that intentionally immigrated and isolated themselves for centuries to fulfill some kind of prophecy, came into contact with technologically-advanced invaders, and resisted to a degree but were partially tainted.
- The Immortal Queensguard are a tribe of Japanese samurai whose only desire is to protect Queen Himiko until she can devour a new host. They love murdering outsiders to their island, especially those who think they can set up their own cult around Himiko, but the latest cult has proven difficult to fight and is armed with modern weapons. Lara fights her way through these maniacs, captures their queen while she's switching bodies, and Trinity purges the rest.
- The Followers of the Prophet are the descendants of the lost city of Kitezh, which was composed of middle-eastern travellers who made their way to Siberia to protect a Prophet's Crystal that gave immortality to hundreds, but fell to insanity when the Deathless Army decided they didn't need the lower class. Soviets invaded the village, the hunters fought back and won, but took the equipment to boost their combat strength. Decades later, Lara fulfills their purpose by destroying the Crystal, but the villagers part ways due to a lack of leadership.
- Paititi is a small village in Peru made of survivors from various Aztec and Incan calamities who have sworn to protect Pandora's Box... except the box has been missing for centuries and no-one noticed. Lara accidentally began the apocalypse when she stole the key to the box, and stormed her way into Paititi to fix her mistake only to find Trinity made it their home base for centuries, with Amaru Dominguez as both leader of the city and Trinity itself. The city itself has an Enforced Technology Ban and nobody can show off anything more advanced than a metal bow and some obsidian-studded clubs. Eventually, Lara shanks Amaru and uses the box's power to stop the Apocalypse.
- Wikipedia has an article on this subject.
- Perhaps the best example of this trope in real life are the Sentinelese tribe, which may very well be the most isolated group of indigenous people on Earth. They live on North Sentinel Island in the Andaman Islands of India, living a hunter-gatherer lifestyle that hasn't changed much since the Stone Age. They violently reject all attempts at contact, shooting at any outsiders with arrows. Because of that, we know next to nothing about them, including their culture, language, and religion. The last official attempt at contact was made in the mid 1990s, and since then they've been left alone, and it's very unlikely that will change anytime soon. Indian law forbids any attempt to come within an exclusion zone around the island, both for the protection of the tribespeople given they haven't been exposed to many infectious diseases, and because they tend to kill outsiders who land on their island even by accident. Their numbers may or may not have been culled considerably by the 2004 Indian Ocean tsunami, but good luck trying to find out yourself. The last person to set foot on the island, a Chinese-American Christian missionary named John Allen Chau in late 2018, was killed by the natives when he trespassed and refused to leave, even after they'd already shot arrows at him once.
- Lost tribes of Native North Americans are found all the time. They live like modern people and are really not all that different. In some cases they're not really "lost" at all, just not recognized as a tribe by the US or Canadian governments.
- Previously unknown offshoots of the Jewish diaspora show up every decade or so, though many groups make up stories of Israelite descent as well.