Arabia is mostly made of desert, inhabited mainly by nomad tribes during the 7th century. On the shores of the Red Sea and Indian Ocean, fertile areas with many flourishing settlements were found, but the products were mainly local. The trade roads led to Syria and Mesopotamia (Iraq). Prosperous oases were found on the commercial routes, like Mecca and Medina, and the agriculture in the arid areas was possible using waterwheels and irrigation ditches. The kingdom of Sheba, in Yemen, was signaled even from the Bible and maintained trade contacts with eastern Africa, Ethiopia, Egypt, Persia and the Greeks.
During the Christian era, many Arab areas received influences from the heretic Nestorian and Monophysite churches. Each tribe was independent and led by a sheik. This mosaic of nations knew unity only in limited occasions, like after the intervention of an Ethiopian Christian king, who found about the religious persecution triggered by Himyarite king (in southern Arabia), who had converted to the Mosaic religion. The campaigns of the Sassanid Persians agglutinated sometimes the tribes as well.
But the definitive unity and expansion came with the Islam. The prophet Muhammad was born in Mecca, son of a camel herder, in 571. He lost both parents when young and was looked after by an uncle. By the age of 25, in 596, he accompanied camel caravans and married his mistress, already twice widow, Khadijah. Muhammad traveled alone a lot through the mountains and after his marriage, around 610, he experienced an odd incident. He had visions in which he spoke to Archangel Gabriel, marking down his instructions in verses. These writings make the first part of the holy book of the Islam, the Koran. The final book comprises 122 percepts received by the prophet in 22 years.
Meanwhile, Muhammad started to preach, claiming that there was only one way for salvation: total obedience to the mighty God. This is the meaning of the word "Islam" in Arabic. The adepts of Islam were Muslims - "submissive, indulgent".
Muhammad founded a religious community made of his few disciples and his family members, but it was not popular in the city. The welfare of the city of Mecca was due especially to the pilgrims coming for worship at the Kaaba stone, a sanctuary dedicated to a number of about 360 gods and spirits. But the new prophet stated that any god or spirit was false, and the situation turned so dangerous that Muhammad and his disciples had to leave the city in 622. This displacement was called Hidjra and it is considered the start of the Islamic period.
Muhammad found shelter in the nearby city of Medina where he turned into an important man, being a judge. He was acknowledged to be the prophet of Allah and leader of the city against its numerous military campaigns of Mecca. When Mecca surrounded in 630, Muhammad destroyed the 360 idols and offered Kaaba to Allah.
Muslims have to pray 5 times a day. In the cities, the call to prayer is made by the muezzin from the top of the mosque's tower. In that moment, craftsmen, traders or farmers, have to cease their activity, put on the ground a small carpet to kneel on and pray looking towards Mecca. No believer can die before visiting the Holy City of Muhammad. In other times, this meant months and years, during a dangerous voyage.
The Muslim man can have a maximum of four wives, if he can take care of all of them equally. Women are not authorized to maintain social contacts of any type. The harem is accessed only by the husband and the sons, and women cannot have public functions. Almost in all Islamic areas, the women have to wear a veil.
The Koran says that the Muslim who dies defending the Islam will go to paradise, being looked after by 72 beautiful virgins.
Until the death of the prophet in 632, almost all Arabia had turned to Islam. As Muhammad had not nominated a successor, conflicts emerged between his relatives, followed by revolts, rebellions and civil wars in the peninsula.
The conflict came to an end when a deal was made between the adepts of the prophet. A caliph (disciple, adept) took the succession and the Arabs started their conquests. The tribes that previously had fought one another were then united and troubled the two super-powers dominating the Middle East: the Greek Christian Byzantine Empire and Sassanid Zoroastrian Persia.
The first caliph was Muhammad's father-in-law Abu Bakr (632-632 AD) but the conquests started during the caliph Omar (634-644). In 635, he conquered Damask and in 636, the army chief Halid ibn-al-Walid destroyed the Byzantine Army in the battle of Yarmouk and drove it away from Syria. Then, the Muslims invaded Mesopotamia, dominated by Persia, and in 642 they occupied Persia and Alexandria (and with it, the whole Egypt). From Egypt, further campaigns conquered Northern Africa. Meanwhile, the Islamic Empire was weakened by the fight between the Arab tribes that formed different nations. The third caliph, Osman (644-656) was killed and its successor was chosen Muhammad's cousin, Ali (656-661). The riots continued and Ali was killed. His disciples refused to obey the successor caliph, Muawiyah, and proclaimed autonomy. This was the definitive schism between the majority of Sunni Muslims and the Shi'a minority. Many sects appeared later, but this rupture was fundamental.
Ali's death ended the classic caliphate and Muawiyah (661-680) started ruling like a king from the Syrian capital, Damask. The title was to be inherited by the king's son or a close relative and the rule was exerted with the help of a centralized social structure, which was not characteristic for the Arab states. Muawiyah founded the first dynasty of caliphs, Umayyad, but its power crystallized only after Abdal-Malik (685-705) gained the 30 years inner war. With the new order installed, the campaigns continued: Muslim forces went to Tashkent, conquered Sind and a part of Punjab (India) and, through the Gibraltar strait, entered Spain in 711, conquering it almost entirely. In 718, the Arabs crossed the Pyrenees Mountains, reaching central France where they were crashed by Franks, at Tours in 732. Further conquests in Europe were stopped.
Under the Umayyad dynasty, the Islamic Empire had reached its peak: trade could be made undisturbed from Spain to India. Unlike other conquerors, Arabs learned with pleasure from other nations, adopting their way of ruling the state, army organization and Byzantine and Persian navigation; they learned from the science and art of the subdued nations.
Usually, the Muslims were tolerant with the Non-Muslims, especially "The People of the Book" (Christians and Jews), with biblical traditions similar to theirs. The Islam considered Abraham and Moses real prophets, whose work was completed by Muhammad. Muslims were tax free, unlike the Non-Muslims. This was a motivation on long term for many people to convert to Islam. As Koran's translation to other languages was forbidden, many new adepts had to learn Arabic, so that the conquered people were easier assimilated. When this happened, an Arab was considered a person speaking the Arabic language and with the same religion and culture.
But the tolerance of the Umayyads meant the end of the dynasty. Many subjects considered they did not take care enough to convert the Non-Muslims. Religious discontent and riots of the Arabs from Iran and Mesopotamia, unhappy to be led from Damask, caused a big rebellion in 747, whose leader was Muhammad's descendant Abdul Abass. In 3 years, all the Umayyads were killed, except Abdar-Rahman, who took refuge in Spain, founding an autonomous dynasty that lasted 300 years.
The Abassid dynasty founded a new capital in Mesopotamia: Baghdad, which soon would have 1 million of inhabitants. Special interest was in the conversion to Islam and the adoption of the Arab languages. Only Persia kept its language, the Persian, and its cultural identity, but turned from Zoroastrian into Muslim.
This is the peak of Islamic culture. The caliph Al Mansur (712-775) founded "The Palace of the Knowledge" were savants could translate the works of the ancient Greek philosophers, studied ancient medicine, learned Indian mathematics (the numbers, invented by Indians, are known as Arabic numbers, because Arabs brought them to Europe). The Persian Ibn-Seena (Avicenna), a philosopher and medic, was famous even in Europe. Algebra is an Arab word, and Arab mathematicians founded this subject. Omar Hajjam (1048-1131) was a great Persian mathematician, astrologist and poet.
Literature and art flourished. Mosques and palaces adorned with colored ceramics were built. Arabesques reproduced plant and animal motifs, combined with lines of Arab writings. The collection of Asian stories called "The Book of One Thousand and One Nights" has become a classic one. Islamic science and culture pushed its contemporary Europe a few centuries forward. Western world took many of the Arab sources of science, philosophy, mathematics and medicine (even the method of paper making, invented by the Chinese, reached Europe through the Arabs).
But the huge empire was hard to control; a new dynasty arose in North Africa: the Fatimids (909-1171), who established their capital at Cairo.
In time, the political power of the Persians grew, and the Abassid caliphs turned into puppets of the Persian rulers. Things got even more complicated when the Turks, nomadic Mongoloid (at origin) tribes, coming from Central Asia, occupied most of the Islamic Near East, ruling it in the name of the Abassid caliphs, their leader being the sultan ("ruler") between 1055-1157. The Turks were skilled warriors and forced the Byzantines to ask for the help of Western Europe. This is how the Crusades started.
By the 12th century, the Caliphate was divided in small sultanates. But the Turks resisted and responded to Crusades. The caliphate was over when the Mongol hordes sacked Baghdad in 1258.