the Gulf of Suez and the Gulf of Aqaba of the Red Sea. It is linked to the African continent by the Isthmus of Suez, wide strip of land, containing the Suez Canal. The eastern isthmus, linking it to the Asian mainland, is around wide. The peninsula's eastern shore separates the Arabian plate from the African plate. The southernmost tip is the Ras Muhammad National Park. Most of the Sinai Peninsula is divided among the two governorates of Egypt: South Sinai (Ganub Sina) and North Sinai (Shamal Sina). Together, they comprise around 60,000 square kilometres (23,000 sq mi) and have a population (January 2013) of 597,000. Three more governates span the Suez Canal, crossing into African Egypt: Suez (el-Sewais) is on the southern end of the Suez Canal, Ismailia (el-Isma'ileyyah) in the centre, and Port Said in the north. The largest city of Sinai is Arish, capital of the North Sinai, with around 160,000 residents. Other larger settlements include Sharm el-Sheikh and El-Tor, on the southern coast. Inland Sinai is arid (effectively a desert), mountainous and sparsely populated, the largest settlements being Saint Catherine and Nekhel. Climate Sinai is one of the coldest provinces in Egypt because of its high altitudes and mountainous topographies. Winter temperatures in some of Sinai's cities and towns reach . History Chalcolithic A cave with paintings of people and animals was discovered about north of Mount Catherine in January 2020, dates back to the Chalcolithic Period, circa 5th–4th millennium BCE. Ancient Egypt From the time of the First Dynasty or before, the Egyptians mined turquoise in Sinai at two locations, now called by their Egyptian Arabic names Wadi Magharah and Serabit El Khadim. The mines were worked intermittently and on a seasonal basis for thousands of years. Modern attempts to exploit the deposits have been unprofitable. These may be the first historically attested mines. The fortress Tjaru in western Sinai was a place of banishment for Egyptian criminals. The Way of Horus connected it across northern Sinai with ancient Canaan. Achaemenid Persian Period At the end of the time of Darius I, the Great (521–486 BCE) Sinai was part of the Persian province of Abar-Nahra, which means 'beyond the river [Euphrates]'. Cambyses successfully managed the crossing of the hostile Sinai Desert, traditionally Egypt's first and strongest line of defence, and brought the Egyptians under Psamtik III, son and successor of Ahmose, to battle at Pelusium.