Someone reading “Heroes of the Elemental Chaos” might immediately think of it as a companion supplement to “The Plane Below: Secrets of the Elemental Chaos”. And that is certainly the case in many respects since many of the topics are focused on the Elemental Chaos rather than any particular setting. However, it’s no surprise that the Elemental Chaos has a place in the Dark Sun setting since a portion of the setting revolves around the elements, both in the prevalence of elemental beings and how mortals utilize elemental power. The 4e Dark Sun Campaign Setting even goes so far as to note its connection with the Elemental Chaos with references to the primordial Ul-Athra as well as describing portals to the Plane Below (e.g. Dhuurghaz: The largest island in the Road of Fire).
This is a companion discussion topic for the original entry at http://athas.org/articles/heroes-of-the-elemental-chaos-as-a-dark-sun-supplement