The Battle Zone
It is believed that this island was once connected to mainland Sinnoh via several land bridges, the largest being just northeast of Veilstone City. Several tribes of prehistoric people migrated there around the same time Unova's Relic Castle was built. There is record of these people feeling enmity towards those on the mainland, and actively wanting to separate. One might even speculate that they helped along the destruction of the land bridge two hundred years later.
These separatists led a very different lifestyle than other Sinnohans. They constantly sparred with the alarmingly strong native Pokémon for food and shelter, and befriended only those that they considered equals. To this day, they maintain their minimalistic traditions of training few Pokémon.
When mainland Sinnohans rediscovered the island some 1000 years ago, they marveled at how differently their societies had developed – but not for long. Soon, the natives were overpowered by the more technologically-advanced invaders, who quickly built settlements and decimated the wild Pokémon population far more than the original inhabitants. Tribes of natives today are few and far-between, and are usually only found east of the Survival Area and Stark Mountain. They tend to be a more docile people than their ancestors, but can still be hostile if their land is disturbed in any way.
Since these native people migrated to the Battle Zone before signs of a written language were invented in the caves of Solaceon Town, stories were passed orally through generations. The single most famous of these stories surprisingly does not detail hostilities between the Sinnohans and natives, but rather one friendly relationship that changed the lives of many. This may suggest that not all of the natives believed in the separatist ideas of the majority.
The story varies slightly among tribes, but the basics are constant: A young explorer ventures too far from home and loses his way in the twisting forests that once covered the region. He emerges in the midst of an intense battle between two native Pokémon and receives mortal wounds, only to be rescued and healed by a native girl. He must gain the trust of her people before he can be accepted into their family. Having reached the ears of the ever-present Sinnoh Entertainment, the story is scheduled to be filmed sometime in the next year. How they will capture the archaic tale remains unknown.
A/N: Welcome to my newest multi-chapter attempt! I'm hoping to make this a series of history tidbits about the places of the Pokémon world, particularly Sinnoh. The thing is, though, that you get to choose what comes next! Below is a list of three possible topics for chapter 2. You get to vote in a review, and I'll write whichever one has the most votes. If you really hate the choices, you can suggest another one, and I'll consider writing that instead.
Topic of the next chapter:
A. Canalave City
B. Eterna Forest
C. Jubilife City
Happy voting!
~Ebaz