DIRIYAH, Saudi Arabia — More than 250 years ago, in this sunbaked oasis of mud-brick houses and ramparts, the ancestors of the Saudi royal family and an outcast fundamentalist preacher formed an alliance that has shaped this land ever since.

In return for political supremacy, the House of Saud endorsed the doctrine of Sheikh Muhammad ibn Abdul-Wahhab and followed it to wage jihad against anyone who rejected their creed, gaining control of much of the Arabian Peninsula.

That alliance laid the foundations of the modern Saudi state, which has in more recent times used its oil wealth to make the cleric’s rigid doctrine — widely known as Wahhabism — a major force in the Muslim world.

And now, this site, the birthplace of it all, is becoming a tourist attraction.

Inside a massive complex on the outskirts of Riyadh filled with parks, restaurants and coffee shops, hundreds of laborers are rehabilitating mud palaces once home to the Saud family and building museums celebrating its history. Nearby stands a sleek structure that will house a foundation dedicated to the sheikh and his mission.