sentences:  Much of the Regency is included in the Mount Sewu (literally "thousand mountains") collection of limestone hills which stretches across parts of southern Java from parts of Kebumen Regency in the west near the border with West Java across to close to the city of Malang in East Java.The Menoreh Hills in the area south of Yogyakarta in Kulonprogo Regency, for example, are part of this series of limestone hills.The limestone hills are reported to contain hundreds of caves.