Elementals have existed in Faerune from right around its initial creation. They may or may not have been the first beings to inhabit the planet. While many may be old they are still wild, uncontrollable, and sentient in a way no mortal understands. They do not even view time, or at least in the same sense most mortals do and thus have never recorded their history except for great cataclysmic events.
They have never expanded into para types (ice, wood, mist, etc) and remain pure to their elements: Fire, Water, Earth, & Wind.
Individuality is not important to an elemental, and thus they tend to look only roughly humanoid at best. Their element is their body.
Depending on their type, the habitat will change. They are rarely found away from a suitable habitat.
Fire types stick lose to hot places, such as volcanoes and even hot springs.
Water types will stay near any body of water, moving or not.
Earth types stay closer to larger ground formations such as mountains.
Wind types stay in open planes or places where trees and other objects do not obscure the wind.
Ancient in most cases. They are often older than dragons, as an elemental does not have the normal mortality of most living beings.