Terra Sabaea is a large area on Mars. It was named in 1979 after a classic albedo feature on the planet. Terra Sabaea is fairly large and parts of it are found in five quadrangles: Arabia quadrangle, Syrtis Major quadrangle, Iapygia quadrangle, Ismenius Lacus quadrangle, and Sinus Sabaeus quadrangle. (wikipedia entry)
A terra is an extensive land mass. On Mars they are named after the nearest named albedo feature on the Schiaparelli or Antoniadi maps.