A savannah was an area of land characterised by temperate weather, dry grassland, and largely flat terrain.
The Flux Savannah was a region of the planet Flux. It was a harsh area, with flat, rocky red soil, baked to diamond-like hardness. There were only two species known to live in the Flux Savannah: the Suckweed and the Soresox. (PROSE: The Doctor Trap)
More biodiverse savannahs made up the vast majority of the Catkind's homeworld, New Savannah. (COMIC: Agent Provocateur)