Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in West Asia and the Middle East. It covers the bulk of the Arabian Peninsula and has a land area of about 2,150,000 km² (830,000 sq mi), making it the fifth-largest country in Asia and the largest in the Middle East. It is bordered by the Red Sea to the west; Jordan, Iraq, and Kuwait to the north; the Persian Gulf, Bahrain, Qatar and the United Arab Emirates to the east; Oman to the southeast; and Yemen to the south. The Gulf of Aqaba in the northwest separates Saudi Arabia from Egypt and Israel. 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. The capital and largest city is Riyadh; other major cities include Jeddah and the two holiest cities in Islam, Mecca and Medina. With a population of almost 32.2 million, Saudi Arabia is the fourth most populous country in the Arab world.

Pre-Islamic Arabia, the territory that constitutes modern-day 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 outside Africa. Islam, the world's second-largest religion, emerged in what is now Saudi Arabia in the early seventh century. Islamic prophet Muhammad united the population of the Arabian Peninsula and created a single Islamic religious polity.