As one of the planet’s largest religions, with adherents in dozens of countries, Islam has achieved significant and widespread impact. As with most world religions, Islam’s roots can be traced to a singular individual in a particular place and time.

Saudi Arabia

Islam was born in the nation today known as Saudi Arabia, located on the Arabian Peninsula between the Persian Gulf and the Red Sea. The kingdom is home to the religion’s two holiest sites, in Medina and Mecca, and, according to the CIA World Factbook, the king of Saudi Arabia’s official title literally means “Custodian of the Two Holy Mosques.”

Mecca

Islam was founded by the Prophet Muhammad, who was born in the year 570 in the western Arabian city of Mecca. In the year 610, Muhammad received a revelation from the angel Gabriel describing the relationship between Allah and his creation and providing a moral and ethical framework for right behavior. The prophet was told to recite the teachings, which were later written down as the Quran.

Medina

Muhammad’s new monotheistic teachings upset Mecca’s local rulers, who worshiped a plethora of gods, and the prophet and his band of followers were forced to relocate to the city of Medina in 622. Muhammad’s house in Medina became a model for the architecture of the Muslim mosque, according to Suzan Yalman, writing for the Heilbrunn Timeline of Art History at the Metropolitan Museum of Art, and after the number of Muhammad’s followers had grown significantly, he eventually returned to Mecca. There he removed all of the idols from the city’s primary shrine and dedicated the holy spot to Allah.

Spread of Islam

Despite Islam’s distinctly Arabic roots, S. T. H. Khwarazmi writes in his book “Background of the Birth of Islam” that the Prophet Muhammad’s initial call to faith was a universal one, and he wrote letters to leaders from around the known world of his time. After Muhammad’s death in 632, according to Yalman, the prophet’s caliphs, or successors, led armies which conquered much of the Middle East and brought the Arabian religion and leadership to the rest of the subcontinent.

Mecca and Medina have remained the religion’s celebrated holy sites to this day, and the former annually hosts millions of Muslims making pilgrimages as part of their religious duties. The Oxford Business Group, in an article about the city’s expansion projects to host the growing masses, claims that the city’s population of 1.7 million triples during the Hajj pilgrimage. Clearly, the birthplace of Islam continues to shape the growing religion today.