In the early 7th century, Arabia was a vast peninsula between Africa and Asia, without any linguistic unity: its inhabitants spoke Arabic dialects or South Arabian languages. Few of them knew how to write, and epigraphic certificates were rare until the late 7th century. Monotheism was represented by Judaism and Christianity. Judaism started at a very old age, but was little known. Christianity probably started later: Christian communities lived in the Hejāz and along the caravan routes, especially in southern Arabia, where they lived along the Incense Route, in the main oasis of Najrān, in Hadramout and in Sana'a (Yemen).
Muhammad began preaching in the 7th century in Arabia – the "Island of the Arabs" -, separated from the Mediterranean by a desert and from Asia by a gulf and the Indian Ocean. Islam was not born in a desert. Muhammad's life took place in the Hejāz, a mountain range in western Arabia, and in the urban and business life of the city of Mecca, which was then dominated by the sedentary Quraysh tribe. At the head of a successful pilgrimage, this tribe knew how to build alliances and to protect the caravans from the raids of the Bedouins. The main business trade of caravans was at the hands of Quraysh. This required some financial capital and some skilful practices, as well as building up relations with major civilizations outside Arabia.
The nomadic or sedentary Arab tribes of the peninsula worshiped the tutelary deities, sometimes represented by baetyls, trees, springs or statues. The Quran (The Star, 53:19-20) mentions the triad of "sublime goddesses" al-Lāt (a deity associated with the sun), al-'Uzza and Manāt (whose Arab name suggests fate or death). The Prophet is said to have recited these verses inspired by Satan, hence their name of "Satanic verses". According to the Islamic tradition, these verses are said to have been repealed. A ritual purity was required to address the deities. The worshipers offered them ex-votos that often bore the symbol of the right hand.
The Jewish and Christian monotheisms and Zoroastrism were religions based on new relations with the sacred world, and on prestigious holy books. These religions influenced the Arab polytheism of large tribal confederations, that evolved with new aspirations, as reflected in "monotheistic" inscriptions from the 4th century refering to One merciful God - Rahmanan - in the kingdom of Himyar (Yemen). Their preachers (hanīfs) encouraged a religious reform.
With the Byzantine and Sassanid Empires intervening in southern Arabia, there was a decline of the main caravan routes travelling through the oasis of Najrān, in favor of the Hejāz. Mecca, the birthplace of Muhammad and the center of his first preaching, became a major trade center under the rule of the Quraysh tribe, who also protected the sacred enclosure (haram) around the Ka'ba and who supervised the main annual pilgrimage during fairs.
Muhammad was a man at the center of a tribal system, with its solidarity and its conflicts. His name means "praiseworthy" in Arabic. He is mentioned in the Quran as a "messenger of God." His life is known by the Sirā, the name given to the most famous compilation of ibn Hishām (died in 834) who selected, corrected and revised earlier narratives, especially those of Ibn Ishāq. The term Sirā means "conduct, rule of life." Traditional Islamic sources of the Sirā are late and apologetic. The Sirā is not a historical biography of the Prophet's life, but has belonged to the religious literature offering to believers the idealized figure of a predestined "Messenger" and a "beautiful model" to imitate.
There are very few earlier historical or literary documents external to Islam, except quotes from Theophane, a Byzantine monk. In his Chronografia, a history of the world from Adam to his time (circa 815), Theophane gave some details that would then be transmitted to the Western Christian literature: the marriage of the Prophet with Khadīja, his travels to Palestine, and Khadīja's meeting with the monk Bahīra, who reassures her about the Prophet's vision of the angel Gabriel.
In a break from the tribal beliefs of the time, Muhammad preached the religion of One God that excluded any other belief, a God without rival, an indivisible God – the First Being. God was named Allāh, a common term used by Semitic languages to name the deity. This name probably was of Aramaic origin. The Christians of the Middle East were already using this name to refer to God, before Islam existed. Allāh promised salvation to all humankind who would rely on him. He chose a miracle to reveal his presence and speak to Muhammad, the last prophet in the line of prophets, the "seal of prophecy".
The Islamic literature is rich in narratives on the first revelation of the prophetic mission, on which the Quran gives no information. What is the oldest surah of the Quran "sent down" on Muhammad? What was the role of the angel Gabriel in announcing this mission? The Sunna imposed its version. The Meccan surah entitled Iqrā (surah 96, or at least its first five verses) was considered as the first revelation. The framework narrative of the cave of Hirā - where Muhammad is said to have retreated and met the angel Gabriel - was inspired by a hadīth attributed to 'Ā'isha, the Prophet's young wife. This composition narrative consists of elements scattered in various corpus of traditions, such as a passage of the Bible: “A voice says: “Cry out.” And I said: “What shall I cry?”” (Isaiah, 40:6)
In 622, Muhammad met again with the first emigrant Muslims, the Muhādjirūn,in Yathrib, located 400 miles north of Mecca. The migration of the first small community of Muslims and its leader was negotiated with the Jewish tribes and the polytheist Arab tribes living in the villages of the oasis of Yathrib. Muhammad concluded a pact with some tribes. This historic document is known as the "Constitution of Medina". The period of emigration (from 622 to Muhammad's death in 632) was the one of the second preaching. It was also the time of the armed conflict that Muhammad's first companions and the Ansār (the Medinan auxiliaries who joined them) led against the Meccans and the rebellious tribes.
The Muslim community ('Umma) was extending, with Yathrib soon becoming al-Madīna - the City. This young community of “obedient” people developed new social rules which were more egalitarian than tribal customs, and cemented its unity by setting up similar rules for worship (prayer, fasting, almsgiving, etc.). The community's first place of worship and preaching was the home of Muhammad. The community also adopted the lunar calendar: “It is He [God] who made the sun to be a shining glory and the moon to be a light (of beauty), and measured out stages for her; that you might know the number of years and the count (of time).” (Quran, 10:5) After turning in the direction in Jerusalem, the faithful turned in the direction of Mecca to recite their prayers.
Muhammad died in Medina and was buried there. Muslims of the first post-prophetic generations and of the conquering Islam chose the Medinan Hegira as the start point for the Muslim era. Thus, in the first half of the 7th century, the message claimed by Muhammad was the cement for a new "order" among Medinan converts and then throughout Arabia. This "order" created his own religious symbolism as well as new rules of life and governance.