The religion of Islam was new but passionately followed. It had been established by Prophet / Messenger Mohammed peace be upon him, was born on 570 A.D in Mecca . The belief of that place & time was a blend of ancient Arab tradition, mixed with many Egyptian, Greco-Roman, & Judeo-Christian philosophy. The tradition was somewhat disorganized, with myths coming from different traditions. The people worshipped idols in temples, in the form of statues, making scorched donations.
During his intellectual period, Mohammed ( peace be upon him ) appears to have given a lot of consideration to this, in fact trying to make sense of it all.
When he started advocating the Oneness of God Almighty , the people grew anxious of him, for (to their superstitious minds) this was just pleading for trouble. He was driven out of Mecca along with his family & a few followers . This happened in 622. Muslims call this the hejira, or "migration," & commemorate it even today.
Mohammed's flight from Mecca appears to have solidified, in his mind, the righteousness of his cause. He felt that those who refused to hear him, simply were afraid of "the truth.". Mohammed ( peace be upon him ) his kith and kins went to Yathrib ( Medina ), not very far away from Mecca . Muhammad ( peace be upon him) has hymn the message Of God Almighty for about 13 years to the people of Mecca .
The history tells us that the inhabitants of Medina who have heard the voice / message of truth
which Muhammad ( peace be upon him ) was delivering for thirteen years, they came to messenger
quietly and offered him to come at their city ( Medina ) along with all those who wanted to assist him. He won over most of the population of Medina , & was acclaimed their leader. Muhammad ( peace be upon him ) Has established a system which was based on 100 % Quranic laws decreed by God Almighty , the first ever Islamic State was founded by Messenger Muhammad ( peace be upon him ).
In this era lot of battles broke out in between pagans (Quraysh) and the believers, and except one battle "Uhd" rest all of them were won by believers. During this period political, economical, social and foreign system has been formulated. After 10 years of migration, this jamaat momineen ( believers ) regress to Mecca as a conqueror and they have got the Control of a city with out shedding a single drop of blood .
In 633, Mohammed ( peace be upon him ) passed away. His friend and father-in-law Abu Bakr, took over as head of the Islamic state. The title Ameer ul Momineen " given to all those who have been choosen by the jamaat ul momineen as thier leader signifying that a person was the most righteous, capable and versatile among others.