Koup Region of the Karoo
"The vast swathe of the Great Karoo between the Nuweveldberge or the New Country Mountains in the north and the high ramparts of the Swartberg or the Black Mountains in the south is probably the most desolate and arid region in the Karoo. An area of vast undulating plains bisected by the seldom flowing Buffels, Dwyka and Gamka rivers is bathed in relentless sunlight, blisteringly hot in the summer months and warm during the day in winter with freezing cold nights.
The Koup is the first Karoo region that the traveller encounters on the main highway linking Cape Town and Beaufort West and further north towards Kimberley and Colesberg. It is most often dismissed as a region with little to offer the discerning traveller and most will speed along the main N1 highway intent on traversing the region as quickly as possible. Venture off the main highway and this special region will reveal itself in a jumble of towering mountains, hidden valleys, long sweeping vistas to distant horizons and some of the most beautiful and interesting towns and villages to be found anywhere in the Karoo." Taken from: http://www.karoo-southafrica.co.za/?page_id=132
I am uncertain of the boundaries of the Koup region, so have essentially marked the lower lying flat region bounded by the Nuweveld mountains to the north and the Swartberg mountains in the south and on the east kept to the Western Cape boundary.