The Hagia Sophia is in Istanbul (Turkey).
In its history, it has been a medieval church, a Byzantine Cathedral, and a mosque.
Today, it is a museum for the Ottoman and Byzantine history of the area.
I am not sure about that one chief, but hopefully.
After the emergence of Islam, which was proclaimed by Muhammad, there emerged a caliphate, as an Islamic state under the leadership of the Caliph, a religious leader who represented the religious successor to the Prophet Muhammad. There were three main caliphates, one after the other, during the medieval period: Rashidun Caliphate, Umayyads Caliphate and Abbasid Caliphate. Starting with Umayyads, the title of the caliph became hereditary within the dinasty, and their empire grew rapidly, adding new territories to the Muslim world, reached the situation of the largest empire at that time, and the sixth empire in history. By other Muslims, they were considered too secular.
In the 19th centry it was develop as a concept during the Indian independence movement fought against the British colonel raj
