The definition of Terra Sabaea used by the 2019 JGR paper is the highlands between 60E and Hesperia Planum (~100 E). The southern boundary is along by the escarpment defining the Hellas Basin Rim region, and the northern boundary is the southern edge of Syrtis Major Planum and the Isidis Basin. The Tyrrhena Terra region has 16 mapped bedrock plains.