Compare the Roman Empire and the Caliphate by area and population. That more?

In terms of area, the caliphate of 750 surpassed the Roman Empire of the time of Trajan, but in terms of population it was inferior to it due to the abundance of deserts and areas that were depopulated during the wars.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.