Islamic State under the Prophet
Pre-Islamic Arabia had no central authority. The kind political system varied from place to place. The best was that your tribe would protect against any other tribe. It was ‘each tribe for itself’. They were ready to fight over petty
issues. Seldom did form an alliance. And when they did, it was to fight against the third tribe.
The sovereignty of the tribe customarily lay in the chief of the tribe. The Islamic State formed in Madinah had sovereignty in God. The Prophet was the sovereign Head of the state.
Islam brought the concept of Ummah, where the relationship was based on faith and not on kinship or blood relation.
It is also assumed that Arabia never rose to political prominence on world map because it had no federal/central authority before Islam. The fact is also proven after the emergence of Madinah. Madinah conquered vast lands and got them under the umbrella of State of Madinah.
There was no law of the land, only lawlessness prevailed. In Islamic State, Quran and Sunnah would be the law.
The Prophet as a sovereign
He was the sovereign head of the Islamic State subjected to supreme authority of God. He possessed both spiritual and secular authority & political and judicial powers. He was the supreme commander of Islamic forces and chief administrator of Ummah. He was a ruler and a lawgiver.
The Mosque of Madinah
It was a place of worship, the office, and the court for the Prophet. He performed almost all duties there. He led the prayers there and consulted close companions there. He planned the wars and foreign policy there: all the letters were written there, and each foreign delegate was received there. He resolved judicial matters there and also introduced most of the revelations there, so that they would become the law from thereon. The Mimbar (Pulpit) was a symbol of his sovereign authority. In short, the mosque acted as a secretariat too.
The Provincial Administration
The early Islamic State was a centralized confederacy of the semi-autonomous tribes and a few towns and cities. Usually, the Prophet acted as a supreme chief of every tribe through their tribe chief. Nonetheless, there were places where individuals were sent. Some places were in remote and had little to no knowledge of Islam, so the Prophet sent teams that would rule them and teach them about Islam.
Over the course of time, the Holy Prophet divided the areas into Provincial units. As soon as one area exceeded the proscribed limit, a governor was sent, and it supposedly became a provincial unit. It was done to accommodate the remote tribes from city centers. Khyber and Taif were made provinces so that the tribes and settlement lying in outskirts would also come under the administrative system. The governor performed the duties in same manner as the prophet except the prophetic ones. The laws were to be followed as dictated by the Prophet in Madinah. A Qazi was also sent to each unit. Like governors, these men were of upright character since Islam places high degree of significance on Justice.
For complete Islamic history notes click here.