Who was the ruler known as fifth khalifa?

The ruler known as the "Fifth Khalifa" is Umar ibn Abdul Aziz, who served as the eighth Umayyad caliph from 717 to 720 CE. He is often regarded as one of the most just and effective leaders in Islamic history, noted for his efforts to reform the administration, promote social justice, and support the welfare of the poor. His reign is characterized by a commitment to Islamic principles and a focus on ethical governance. Umar's legacy is remembered for his piety and dedication to the well-being of his subjects.