Unlike gods, who create and maintain their domains, primordials are simply the raw embodiment of them. This makes them incredibly powerful but also incredibly single-minded. They aren't dependent on worshippers the way gods are, but many still ask for their protection simply to be on the safe side.
Primordials awoke early in history. They emerged as some elemental force condensed in one place. The creation then caused an explosion of energies which in turn stabilised regions of the Elemental Chaos. Not all primordials have established themselves as rulers of these domains but rather the centre of them.
Two primordials were created outside, and remain outside the Elemental Chaos. Primus makes their home in Mechanus, while Tyche has made a home in Limbo. Primus rules their realm with absolute control, whereas Tyche mostly uses theirs as somewhere to live.