Ah, that's why they kept encountering Kazon and Hirogen. Hirogen control more space than the Federation, Klingons, Romulans, Ferengi, Cardassians, Breen, Gorn, Tholians, and Tzenkethi combined.
Its based on the travel and the time distances apart from encountering each species, plus even after transwarp corridors they still come upon hirogen, who are supposed to lead hunting parties across the whole quadrant.
They are pretty much like the Bedowin Tribes of the Sahara. Their society is fractured, but do control a massive amount of very uninhabitable space. Over time, they've become vastly separated over 3 quadrants of space, using huge, ancient comms arrays to stay in contact. In the 25th Century, a Beta Quadrant pocket of Hyrogen that borders the remnants of the Romulan Star Empire is recruited - along with the Elachi & Solanae - by the Tal Shiar to sabotage the burgeoning Romulan Republic. They all critically fail of course, when Proconsul D'Tan manages to enlist the aid of the Federation & Klingon Empire. :3