Technically they're inner northwest where the Western Suburbs Panthers, Fortitude Valley Die-hards and Pastoral Brothers Leprechauns were based.
The QRL has down sweet f**k all to expand the BRL/Queensland Cup beyond this proximity. Eastern Suburbs Tigers and Southern Suburbs Magpies are based not too far away from this concentrated part of inner Brisbane. Northern Suburbs Devils are very close to it, too. The only clubs from beyond this region that they introduced were the Redcliffe Dolphins and Wynnum Manly Seagulls. The Ipswich Jets were introduced in te dying says of the BRL and the Logan City Scorpions were brought in to A Grade when it became a second-tier league.
The Crushers were based out of Pastoral Brothers Leprechauns old stomping grounds.
The Easts Tigers were going to create a genuine northwest vs southeast rivalry and have a footprint expanding all the way down the eastern suburbs of Brisbane and Logan. They're now affiliated with the Ipswich Swifts, which suggests they're planning on covering Ipswich as well when they bid again for an NRL licence. You can see their affiliations on their site.