Welcome to the Savage Coast Group! Here's what the Wikipedia has to say about the Savage Coast:
"Mystara includes the Savage Coast, a coastal area located in the south central part of the Brun continent, to the south and west of Hule. This part of Mystara is affected by the Red Curse, a sinister enchantment which eventually kills its inhabitants through mutation unless the (fictional) metal cinnabryl is worn in contact with the body. This area was published in its own boxed set entitled Red Steel, and later republished on-line as the Savage Coast. Its swashbuckling flavor is very different from that of the "Known World", closer in atmosphere to that of the Age of Exploration than the fantasy middle-ages/renaissance tone of the Known World. The Savage Coast is complete with gunpowder ("Smokepowder") weaponry.
The specifics of the "Red Curse", which include mutilation of the body and extreme degeneration of physical and mental health, also tend to keep the inhabitants of the Savage Coast within the region, as debilitating effects result if they leave the cursed area."