The pre-Islamic Arabian peninsula, most of which is today the kingdom of Saudi Arabia, was populated by the Arab people. The Arabs were herders and merchants. They were organized tribally, with tribes claiming descent from common ancestors and governing through meetings of the patriarchs of each clan. The Arabs were well known in the Roman and Byzantine world as merchants for their camel caravans that linked Europe to a part of the Spice Road, transporting goods from India and China. They were also known to be some of the most fierce and effective mercenary warriors in the eastern Mediterranean region; they rode slim, fast, agile horses and fought as light cavalry.
Arab trade, and population, was concentrated in the more fertile southern and western regions, especially in what is today the country of Yemen. By the late Roman Empire, small but prosperous Arab kingdoms were in diplomatic contact with both Rome and Persia (as well as the Christian kingdom of Ethiopia, then called Aksum). As the wars between Rome and Persia became even more destructive after the Sassanid takeover in 234 CE, the trade routes that used to cross Mesopotamia tended to shift south to sail along the Arabian coast, enriching the Arabs and bringing them into more sustained contact with the major civilizations to their north.
The Arabs were polytheists - they worshiped a variety of gods linked to various oases in the desert. One important holy site that would take on even greater importance after the rise of Islam was the city of Mecca. Mecca had been a major center of trade for centuries, lying at the intersection of trade routes and near oases. In the center of Mecca was a shrine, called the Ka’aba, built around a piece of volcanic rock worshiped as a holy object in various Arabic faiths, and Mecca was a major pilgrimage site for the Arabs well before Islam.