The final Renovation of the Universe

How did muslims father a large army to conquor Persia? First they captured north africa and middle east. What made it possible to go east was they forcibly converted them into muslims, in north africa Where the natives wasnt part of people of the book. They took taxes from those who kept their religion and many did. To further grow. Then byzzantine. Then Persia. Persia was exhausted over centuries of war with the west. India remained strong. Persians invaded india but left shortly after. The islamic invasion couldnt last long because of the severity of loss they took in India. Magians ( al madjus) are mentioned in the quran, so they could keep their religion, but exhausted from taxes they converted the persians .