What goals did the rulers set? (Charlemagne, Justinian, Harune ar-Rashide)

Charles the Great set the task of creating an empire that would outshine the Roman. However, his state was too short and had not yet developed its own culture to outshine Rome.

Justinian wanted to conquer the entire west in order to restore the Roman Empire under his rule. However, the forces and capabilities of Byzantium were not such as to resist the new barbarian states for a long time. Although Justinian seized a lot of lands, all of his territories were literally bled.

Al Rashid sought to create a state of the enlightened in order to show the scientific nature and greatness of Islamic thought. And convert the whole world to Islam under the influence of culture, not power.