The Jills live in a cozy village made of igloos (which are actually made of brick on the inside and ice on the outside). They live not to far from the large glacier that holds the Phoenix's ancient body, in an area called Brillia. This is also not too far from Mt. Kairus.
The Searchers find shelter here in Episode 46 and again in Episode 47 of the anime series. The inhabitants have worshiped the Cinder Bird for generations.