Bothan space was territory in the Delta Quadrant occupied by the Bothans.
According to inquiries made by Neelix in 2372, there were lots of rumours about ships entering Bothan space, never to be heard from again. His sources on Mithren claimed they had lost several, and that the Botha took protecting their territory very seriously. There was also some belief that the Bothans did not have legitimate claim to the space, and that they were nothing more than vandals.
In 2372, USS Voyager planned to cross Bothan space. In preparation, Tom Paris analyzed the route, and Neelix made inquiries. Upon entering Bothan space, Voyager was quickly confronted by Bothans. (VOY: "Persistence of Vision")