Saudi Founding Day is commemorates the ascent to power of Mohammed bin Saud, who founded the First Saudi State.From Diriyah, the Al Saud dynasty quickly expanded to conquer much of the Arabian Peninsula, including the Hejaz region, home to the holy cities of Makkah and Madinah.His dynasty became known as Al Saud, named after his father, Saud bin Mohammed Al Muqrin, who had ruled Diriyah from 1720, the date often cited as the founding of the dynasty.