Before the leadership of Muhammad, Arabia consisted of mainly nomadic tribes. Many traded in spices which were often used in cosmetics in the ancient world. Community and conformity had a great importance because of the nomadic lifestyle of traders. Caravans meant that quarrels or disagreements often resulted in someone being left behind in the desert to die.
Muhammad came from a family of traders and an influential tribe. He was born in Mecca, in what is now Saudi Arabia in 571 AD. He was an orphan who was brought up by his grandfather and an uncle. He got his first revelation at the age of 40 whilst in a cave three miles from Mecca, where he began to write the Quran, which he said was revealed to him by the angel Gabriel. The Quran was written over a period of 23 years.
Muhammad was said to be very good at solving disputes. He began to acquire an increasing number of followers although he had many opposers. In 622 AD, at the age of 51, he and his followers had to leave Mecca. He began to intercept caravans and rose to power through battles with various tribes but is also described as being a cohesive force amongst factions. He and his followers settled in Medina although he eventually conquered Mecca in 629, three years before his death.
The rift between Sunni and Shia Muslims happened soon after Muhammad’s death. Shia Muslims say Ali, the cousin and son in law of Muhammad was his rightful heir, but might have been prevented from leadership by the original inhabitants of Medina. During his time in Medina, Ali is said to have been his constant companion.
Sunni Muslims preferred the authoritive figure of Muhammad’s father in law, Abu Bakr who took over leadership, but just over two years later he died in battle.
Sunni Muslims constitute 90% of all muslims. Shiites are reported to be the majority in Iran and Iraq only.
Sunni Muslims might be categorized as elitists. Shia Muslims not so much.
Saudi Arabia is ruled by Sunnis which is a dictatorship; the history of which has been an expansion of Arab authority across the middle east. Some people say conversion to what is termed as Islam, a religous system, was on pain of death.
Sunni Arabs were also culturally dominating and the term Arab is now a political rather than cultural designation, causing many middle eastern countries to compromise their own cultural heritage at the behest of Saudi Arabia.
Postscript: Although Saudi Arabia is said to be a relatively modern state, there are biblical references to Yaudi of Arabia who was one of the twelve allies, including Ahab of Israel, who fought for independence from the Assyrian empire in 853 BC.