Answer: They have spread Islam outside Saudi Arabia
Explanation: Caliph was an absolute leader in the Muslim world, more precisely in the caliphate, where he was a religious and state leader. The word caliph means the successor, which refers to the one who succeeded Muhammad. Caliphate was governed by Islamic principles, for which the caliph was responsible, for the purpose of maintaining, strengthening and spreading Islam. Although there were internal disputes after Muhammad's death on the question of Muhammad's successor, this did not prevent the extreme spread of Islam to the rest of the world. As absolute leaders, caliphs began to conquer new territories, whose primary goal, at least according to the basic principles, was to spread the word of God and the prophet Muhammad. Thus caliphs were able to conquer parts of North Africa, then all the way to India, Europe. Later, when Turkish leaders took over the role of caliphs, conquest and Islam spread to a significant part of Europe.