From 1517, under Selim I, the Ottoman Empire began integrating key regions of what would become Saudi Arabia. This expansion included the Hejaz and Asir regions along the Red Sea and the al-Hasa region on the Persian Gulf coast, which were among the most populous areas. While the Ottomans claimed the interior, their control was mostly nominal, varying with the central authority's fluctuating strength over four centuries.^[14]

In the Hejaz, the Sharifs of Mecca retained a significant degree of autonomy, although Ottoman governors and garrisons were often present in Mecca. The control of the al-Hasa region on the eastern side changed hands; it was lost to Arab tribes in the 17th century and later regained by the Ottomans in the 19th century. Throughout this period, the interior regions continued to be governed by numerous tribal leaders, maintaining a system similar to that of previous centuries.^[14]