Ok, a random thought I had a few years ago, that sticks around without being a serious headcanon:
The deep past of Dark Sun is Dragonlance. The Silt Sea? Blood Sea of Istar.
Not gonna lie, this runs into major problems if you think about it too long or look at the map too closely, but it does give you some ideas for further development.
It also means that the halfling progenitors of long ago that the rhul-thaun look up to? They were kender. 
Maybe Dark Sun is the result if the whole Chaos War/War of Souls thing had gone wrong. The gods are gone, but instead of the War of Souls happening, somebody discovers defiling magic…
Or even just Vance-style “Tales of the Dying Earth”… 10,000 years is a really long time ago (and it will give you such a crick in the neck)
Somewhat unrelated, but at least unrelated to both things:
We rag on Dark Sun, rightfully, about its lack of continuity sometimes, but every so often I recall that, in the novel Kendermore, a character is, and is recognized as, a half-orc, despite there being no orcs on Krynn.