The coasts of the peninsula are, on the west the Red Sea and the Gulf of Aqaba, on the southeast the Arabian Sea (part of the Indian Ocean), and on the northeast, the Gulf of Oman, the Strait of Hormuz, and the Persian Gulf.

Its northern limit is defined by the Iranian and Iraqi mountain range of Zagros collision zone, a mountainous uplift where a continental collision between the Arabian Plate and Asia is occurring. It merges with the Syrian Desert with no clear line of demarcation.

Geographically, the Arabian Peninsula includes the western regions of Iraq and parts of Syria. Politically, however, the peninsula is separated from the rest of Asia by the Euphrates river. The following countries are politically considered part of the peninsula:

• Bahrain, an island nation off the east coast of the peninsula.
• Kuwait
• Oman
• Qatar
• Saudi Arabia
• Jordan
• United Arab Emirates
• Yemen, the sole republic on the peninsula.

With the exception of Yemen and Jordan, these countries (called the Arab Gulf states) are among the wealthiest in the world.

As of 2008, the estimated population of the Arabian Peninsula is 71,983,936.

Ancient history

In his book, 'The Real Eve', Oppenheimer claims based on mitochondrial evidence in conjunction with the contemporary environment (ie glaciation, sea levels) corresponding to these molecular clock timelines that the very first humans to leave Africa crossed the virtually dry mouth of the Red Sea onto the Arabian peninsula. They travelled along the coastline of the peninsula before crossing into Southern Asia.

The earliest known events in Arabian history are migrations from the peninsula into neighbouring areas . Around 3500 BC, Semitic-speaking peoples of Arabian origin migrated into the valley of the Tigris and Euphrates rivers in Mesopotamia, supplanted the Summerians, as the Akkadians (see Babylonia and Assyria). Some archeologists argue that another group of Semites left Arabia around 2500 BC during the Early Bronze Age Amorites and settled along the Levant mixing in with the local populations there. These Amorites eventually became the Arameans and Canaanites of later times Bernard Lewis mentions in his book The Arabs in History:

"According to this, Arabia was originally a land of great fertility and the first home of the Semitic peoples. Through the millennia it has been undergoing a process of steady desiccation, a drying up of wealth and waterways and a spread of the desert at the expense of the cultivable land. The declining productivity of the peninsula, together with the increase in the number of the inhabitants, led to a series of crises of overpopulation and consequently to a recurring cycle of invasions of the neighbouring countries by the Semitic peoples of the peninsula. It was these crises that carried the Assyrians, Aramaeans, Canaanites (including the Phoenicians), and finally the Arabs themselves into the Fertile Crescent."