The geography in Afghanistan is varied, but is mostly mountainous and rugged, with some unusual mountain ridges accompanied by plateaus and river basins. It is dominated by the Hindu Kush range, the western extension of the Himalayas that stretches to eastern Tibet via the Pamir Mountains and Karakoram Mountains in Afghanistan's far north-east. Most of the highest points are in the east consisting of fertile mountain valleys. The Hindu Kush ends at the west-central highlands, creating plains in the north and southwest, namely the Turkestan Plains and the Sistan Basin; these two regions consist of rolling grasslands and semi-deserts, and hot windy deserts, respectively. Forests exist in the corridor between Nuristan and Paktika provinces, and tundra in the north-east. The country's highest point is Noshaq, at above sea level. The lowest point lies in Jowzjan Province along the Amu River bank, at above sea level.