Not every culture sits neatly inside a capital. These peoples are fully playable, not flavor text.
SUN WARRIORS
A living hidden culture, not a ruin, that keeps the original firebending philosophy and honors the eternal dragons Ran and Shaw. Chief Aniruh holds the fire-dance plaza in the Circle of the Eternal Sun. Priestess Solari keeps the Temple of the First Flame. Ran and Shaw roost in the Cave of the Masters. They test; they do not perform. They may refuse anyone who smells of a fresh dragon kill. Outsiders are not welcome without a trial. During Sozin's hunts, revealing this city is dangerous. A worthy PC may learn the Dancing Dragon here. A trophy-hunter PC may die here. The Sun Warriors know dragon hunts are a spiritual crime. They are not a random side dungeon on the way to the Caldera.
KYOSHI ISLANDERS
Founded and raised in Avatar Kyoshi's legal and cultural shadow. Independent, wary of both Earth King and Fire Lord. The Kyoshi Warriors are a trained, mostly nonbender guard in fans, makeup, armor, and iron discipline. Headwoman Oyuki works the village dojo and the Unagi Shrine hall. She has an old White Lotus tile she does not advertise. Michi holds the Main Village Gate. The Unagi is a territorial sea serpent in the harbor, a living wall, not a boss to farm. Fire sails have been sighted in the eastern sea. Oyuki wants scouts, not speeches. Relics and masterwork fans live in the shrine and dojo. A Kyoshi Warrior PC is a complete nonbender path with rank titles from Initiate to Headwoman's circle to Legend.
LAMBAK CLAN
People of Lambak Island, a Fire Nation "special region" from the Roku-era novels, granted strained autonomy after the island conflict. Chief Dumalaga holds the Clan Longhouse and talks autonomy while making harder bargains in private. Dalisay, elderly, morally myopic, works the Spirit-Metal Foundry's inner laboratory and is stockpiling for a dated operation. Kozaru holds the Special Region Garrison Gate and command loft. Spirit-infused metal is real here: lighter, stronger, spiritually noisy. Much of it is going to the Crimson Mandate, not just the clan. Questline: Lambak Steel — what is being forged for a war that does not exist yet. A Lambak PC may love the island, hate the foundry contracts, or work them.
SI WONG TRIBES
Desert people, including sandbenders who treat loose sand as earth. They keep their own counsel, sail dunes, and often trade with beetle-headed merchants. Kingdom tax men are not friends. Sandbending is known among them and awkward for packed-stone earthbenders until trained. Krik sells maps and beetle-glass at a dune-market tent and can guide a party toward the Library for a price and a reason. Wan Shi Tong's Library sits under the sand: entrance descent, central nest, west wing stacks. The owl already has comet-cycle material and is in a bad mood about war plans. Knowledge seekers, fox-like, including Dart, report "war tourists." Visitors must add knowledge. A Si Wong PC is a full earth path with @Sand-Sail and desert navigation, not a lost tourist in someone else's kingdom.
COLONIAL MIXED-HERITAGE
Children of Fire settlers and Earth Kingdom families in Yu Dao and other western colonies. Bilingual, politically exposed, caught between empire and home. The colonies already prosper and complicate any clean withdrawal. A colonial PC can walk both markets and be trusted by neither court. See the Yu Dao lore page.
SPIRIT-TOUCHED AND OTHER BORDERS
Some people of any nation carry a spirit mark: dreams, attraction of spirits, danger from Koh. This is an original lineage category, not a hidden canon race. Foggy Swamp kin are listed with the Water Tribes but live inside the Earth Kingdom's interior and should feel distinct. Hidden does not mean unavailable. If a player wants to be a Sun Warrior, a Kyoshi Islander, a Lambak smith, or a sand-sailor, start them at the matching POI and take the secrecy seriously.