They cover an area of 1,909 square kilometres (737 sq mi) and are the largest Slovenian mesoregion.
[1] The Savinja flows through the hills transversely from the Celje Basin and joins the Sava at Zidani Most.
The settlements Litija in the Litija Basin and Trbovlje, Zagorje ob Savi, and Hrastnik in the narrow Central Sava Valley are known by their mining and timber rafting past and the energetics industry.
The town of Radeče at the beginning of the wider Lower Sava Valley is known after paper industry.
Other economic activities in the region are services, forestry, and livestock production.