Saudi Arabia, officially the Kingdom of Saudi Arabia, is a country in Western Asia. It spans the vast majority of the Arabian Peninsula, with a land area of approximately 2,150,000 km². Saudi Arabia is the largest country in the Middle East, and the second-largest country in the Arab world. It is bordered by Jordan and Iraq to the north, Kuwait to the northeast, Qatar, Bahrain, and the United Arab Emirates to the east, Oman to the southeast and Yemen to the south; it is separated from Egypt and Israel in the north-west by the Gulf of Aqaba. Saudi Arabia is the only country with a coastline along both the Red Sea and the Persian Gulf, and most of its terrain consists of arid desert, lowland, steppe and mountains. Its capital and largest city is Riyadh, with Mecca and Medina serving as important cultural and religious centers.
The territory that now constitutes Saudi Arabia was the site of several ancient cultures and civilizations. The prehistory of Saudi Arabia shows some of the earliest traces of human activity in the world. The world's second-largest religion, Islam, emerged in modern-day Saudi Arabia.