Islam:  literally "submission to the will of Allah."  It is the third great monotheism, which originated in Arabia early in the 7th century.
Mohammed [c. 570-632]:  the prophet who founded Islam.
For thousands of years, the Arabian peninsula, which is the original home of the Arab people, had periodically sent out waves of invaders.  These invaders, who spoke semitic languages, had swept northward into the more fertile river valleys of the Tigris and Euphrates or toward the coast of the Mediterranean Sea.  In the year 600, it had been a long time since the last group of these Semitic-speaking invaders had poured forth from the peninsula; and even the most astute observer would have been hard put to predict any Arab expansion whatsoever, not to mention the one which soon afterwards occurred.
Semites:  those who speak semitic languages, such as Hebrew and Arabic.
Semitic languages:  a group of closely related languages, which appear to have evolved from a common mother tongue.  Consequently, all semitic languages are members of a language family, comparable to that other great language family-- Indo-European.  The home of the semitic language family is the great desert of Arabia, which lies south of the Fertile Crescent.
To all appearances, in the year 600, the Arabs seemed willing to remain in their ancestral homeland, riding their camels, tending their flocks of sheep and goats, raising the fine horses for which they were especially noted, and fighting among themselves.
Like the early Germans, the Arabs were pastoral nomads who enjoyed warfare, both as a recreational activity and a means of supplementing their meagre income.
Arab society was patriarchal; in other words, organized into male-dominated families.  Families were grouped into tribes ruled by sheiks, many of whom were elected by the male heads of families.
Blood feud:  characteristic form of private justice practiced by the Arabs in which a family avenged any injury to a member.
Infanticide:  the killing of unwanted infants.
The blood feud and infanticide together probably constituted an important check on population expansion.
Historians speculate that drunkenness may have been a significant vice in early Arab society, resulting in Mohamed's ban on alcohol.
Like the Germans, the Arabs were courageous and hospitable people; and they had a great love of poetry and story-telling.
By the 7th century, the Arabs had already adopted a written script based on the same alphabet earlier adopted by the Greeks, Romans, and Germans.  (The movement of the alphabet since about 1000 B. C. is one the prime examples of cultural diffusion.)
By the late 6th century, while most of the Arabian population remained nomadic, some people had begun to settle down in cities, the most important of which were Mecca and Yathrib [Medina].
Hejaz:  The most advanced region of Arabia, located along the Red Sea coast.  This area benefitted both economically and culturally from the ancient east-west trade route which passed through the Red Sea.   As a result, it was here that the cities were located.
Mecca:  the birthplace of Mohammed and the religious capital of Islam. 
Note:  Even before the birth of Islam, Mecca was the religious capital; however, at that time, it was the center of the polytheistic religion which the Arabs practiced before Mohammed's religious reforms.  There was, however, a dawning belief in a more universal deity, called Allah-Taala ["God Almighty"], but he did not as yet play much of a role in Arab religion.
Mohammed, who came from a poor family, appears to have been raised as a shepherd.  Eventually, he became a camel driver, travelling widely in the Near East.  During this period, he worked his way up to caravan leader; and then married the boss.
Khadijah:  wealthy widow in Mecca who married Mohammed.
Importance of this marriage to Mohammed's career:
(1)  It gave him the financial security to be able to pursue his increasing interest in religion.
(2)  It gave him the social position to guarantee an audience (even if no one liked what they heard.)
Apparently, Mohammed first became interested in religion during the long caravan journeys north where he came in contact with other religions, including Judaism, Christianity, and Zoroastrianism.
Even though he seems to have been unable to read or write, he could learn much by word of mouth.
Eventually, Mohammed retired from active participation in the family business.  Increasingly, he devoted himself to religious meditation.  He often retreated into the rugged country outside the city of Mecca; and in the year 611, at about the age of 40, he began to hear a voice in a cave, which identified itself as the archangel Gabriel.  According to Mohammed, the voice commanded him to preach the religion of Islam which means "submission to the will of Allah."  It was around the universal god, Allah-Taala, that Mohammed built the new religion.
Moslem:  the name for anyone who believes in Islam.
Although Mohammed successfully converted his family, most Meccans regarded him not just as a harmless crackpot, but as a very real danger to the city's prestige and economic well-being.  They feared that if the new religion got established in Mecca, it might threaten the city's position as the center of traditional polytheism in Arabia; thereby cutting off the extensive income which pilgrims brought to the city every year.
Kaaba:  square, black stone temple in Mecca which was the central shrine of Arabian polytheism.  Later it would be converted into the central shrine of Islam.
Abu Bekr:  Mohammed's father-in-law and the first leader of the religion [caliph] after the prophet's death.
Caliph:  literally "successor to the prophet"; this is the highest spiritual position in Islam.
At first, Mohammed's family ties protected him; however, following the death of his wife, Khadijah, in 619, matters took a distinct turn for the worse and Mohammed fled to the neighboring city of Yathrib which he renamed Medina, meaning "city of the Prophet.".
Hegira:  Mohammed's flight from Mecca which occurred in 622 A.D.
Islamic Era Date:  The Hegira was of such critical importance in the prophet's career that this became the era date (or, in other words, the year 1) of the Islamic calendar.  Consequently, Moslems date events counting forward and backward from this point in time which, in the Christian calendar, is the year 622 A.D.  Dates in the Christian calendar are given as B. C. (Before Christ) or A. D. (Anno Domini).  In the Islamic calendar, they are either B. H. (Before the Hegira) or A. H. (after the Hegira).
Note:  Students should be prepared to convert a Christian date into the Islamic calendar and vice versa.  For example:
Christian calendar              Islamic calendar
         1 A. D.                         622 B. H.
     622 A. D.                             1 A. H. 
   1000 A. D.                         378 A. H.
   1622 A. D.                       1000 A. H.
Note:  These dates are only approximately correct since the length of the Christian year and the Moslem year are different, one being based on a solar calendar, the other on a lunar calendar.  consequently, over time, the calendars get out of sync.
Mosque:  an Islamic place of worship.
Theocracy:  a form of government where the god is thought to rule through the priest(s) of his religion.  In Medina, Mohammed set up a theocracy, where Allah ruled through him.  This set the pattern for government in an Islamic society where church and the state have been closely connected since the beginning.  The idea that there should be a division of church and state, so prevalent in most western countries today, is foreign to Islam.
Mohammed demonstrated a willingness to use force to spread the new religion.  When the Jewish population of Medina refused to convert, he killed or drove them out.  However, intolerance of this sort is the exception rather than the rule.  Over the centuries, Islam has tended to be more tolerant than Christianity toward religious dissenters who are monotheists.
Once established in Medina, Mohammed converted the desert tribes and led them on raids against the caravans of Mecca. Successful raiding served as a further indication that Allah favored his followers in this lifetime; a failed attack could set back the religion's progress.
Finally, in 630, Mohammed was ready to attack Mecca itself.  The city was taken and forced to convert to Islam, though no blood-bath faced his opponents, only a few of whom were executed.  In fact, the city fathers quickly reconciled themselves to the new faith, when they learned that Mecca would be its religious capital; and that Mohammed would make a pilgrimage to Mecca one of the major requirements for the faithful.
After the conquest of Mecca, most of the rest of Arabia converted; and, by the death of Mohammed in 632, the Arabs stood poised for one of the most remarkable periods of expansion in human history.
Koran:  (literally, "reading" or "recitation") it is the Moslem Holy Book which is the basic source of Islamic theology.  It is a rambling collection of Mohammed's oral teachings, which began to be written down in the years immediately after his death at the command of the first caliph, Abu Bekr.  The definitive version was produced by the third caliph, Othman.
Major beliefs of Islam:
(1)  It is strictly monotheistic: there is no other god but Allah.
(2)  It is a revealed religion.  Allah periodically hands down revelations to special men known as prophets, such as Abraham, Jesus, and Mohammed.  [Islam recognizes twenty-eight such men, including twenty-two Old Testament figures and three from the New Testament, of whom Jesus is one.]
(3)  It is Mohammed who brings God's latest and definitive revelation, which is contained in the Koran.  Thus, Moslems believe that the Koran is a holy book composed under divine inspiration, just like the Bible of the Jews and Christians.
(4)  There are good spirits known as angels; and evil ones known as djin, both of whom interfere in the affairs of humankind.  [The leading angel, or archangel, is Gabriel, who brought Mohammed his revelation.  The leading evil figure is Shaitin, from the Hebrew Satan.]  In other words, Islam believes in divine intervention in human affairs through these spirits.
(5)  There is a belief in a last judgment, followed by permanent residence in heaven or hell.  Not surprisingly, for a desert-born faith, Hell is described as the hottest of deserts, while Heaven is a cool oasis.
Duties required of a good Moslem:
(1)  Repetition of Islamic creed:  "There is no God but Allah and Mohammed is his prophet"
(2)  Prayer five times a day, facing Mecca
(3)  Charity
(4)  Fasting during month of Ramadan
(5)  Once-in-a-lifetime, a pilgrimage to Mecca
Mohammed outlawed drinking, infanticide, and blood feuds, all of which had apparently plagued Arab society before his coming.
Despite his attempts to improve the position of women in Islamic society, they remained on the whole more subjected to male domination than the women of other contemporary societies.
Monogamy:  having a single husband/wife at one time.
Polygamy :  having more than one wife (or husband) at the same time.
Moslem males were/are permitted up to four wives.
Moslems were required to bathe regularly, something which contemporary Christians, with their lesser concern for hygiene, found bizarre.
Reasons for the success of Islam:
(1)  it was a comforting doctrine for a war-like people, since it preached that the slain warrior (much like the Christian martyr) would enjoy instant salvation.
(2)  In addition to paradise, it promised rewards in this world to the true believer who acted according to the dictates of Islam. .
(3)  It turned the Arab's penchant for fighting outward, toward the non-Islamic world.  The razzia, or raid for profit, as well as the jihad or Holy War, were to be redirected against non-believers.
Islam divides the world into two fundamental "houses":  the Dar al-Islam ("the house of Islam") and the Dar al-Harb (the house of war") controlled by non-believers.  Proper aggression is to be directed against the Dar al-Harb.
(4)  The end of the blood feud, internal fighting, and infanticide may have helped supply the population needed to fuel Arab expansion.
(5)  The weakness of the enemies of Islam contributed to Arab success.  The Byzantine and Persian Empires had fought to mutual exhaustion, leaving a power vacuum which the Arabs were in a position to fill.
(6)  The Arabs were also helped by the prevalence of Christian heresies throughout the Near East and North Africa. 
Byzantine emperors had moved against heretics with great zeal.  This was especially true of Justinian, who had firmly established death as the proper penalty for heretics in his great lawcode.  By contrast, the Arabs permitted all monotheists, including Christian heretics, to practice their own religion, as long as they paid the special taxes demanded of non-believers.  Thus, many heretics preferred rule by the Moslem Arabs, rather than rule by orthodox Christians.
A Century of Arab Expansion:  In the decades after Mohammed's death, Arab armies swept out of Arabia, threatening both the Byzantine and Persian Empires, both of which were in a state of exhaustion after several decades of war with one another.  Between 637 and 642, they overran the Persians, after which they continued to move eastward through Central Asia.  Within a century, they had arrived at the Indus River. 
Battle of Nihawand:  Decisive battle for control of Persia.
Meanwhile, they attacked the Byzantines, overrunning Egypt, Palestine, Syria, and North Africa.  For a time, they even penetrated into Asia Minor.  Despite their desert background, they managed to build up a formidible fleet and for a time, seized control over the eastern Mediterranean.  In the late 7th and early 8th centuries, they even threatened the city of Constantinople by both land and sea.
Nevertheless, despite the loss of some of its most important provinces, the Byzantine Empire survived this first great Moslem tide.  Twice within 50 years, imperial forces turned back a joint land and water assaults on Constantinople and drove the Arabs out of Asia Minor.  The major crisis came in the year 717, when another formidible Byzantine emperor, Leo III, broke the Moslem siege of Constantinople by destroying the Arab fleet said to number some 2000 ships.  This ended the first great period of Islamic expansion in the east.
Greek Fire:  Secret weapon developed and used by the Byzantines at this critical moment; it was an incendiary liquid pumped onto enemy ships and set on fire.  Modern science is still not certain of the components.
Thereafter, although the Byzantine Empire never regained Egypt, Syria, Palestine or North Africa, it did retain its two most important provinces - Asia Minor and the Balkan Peninsula.&nbssp; As a result, it was able to continue as an important Mediterranean power until much later in the Middle Ages.
Westward Movement of Islam:  Meanwhile, the forces of Islam also swept westward across North Africa, converting the population as they went.  By 700, the conquest and conversion of the Atlantic coast of Africa was well under way.
In 711, they crossed the straits of Gibraltar and attacked the Visigoths.  Despite the survival of several small Christian strongholds in the northern mountains of Spain, most of the peninsula fell to the Moslems, and for some centuries, Spain became one of the cultural centers of Islam.  Especially important in this respect were the Spanish cities of Cordoba and Toledo.  Following the conquest of Spain, the triumphant Moslems pushed northward into France, arriving in 732 (just 100 years after the prophet's death) at the city of Tours, not far from Paris.
Battle of Tour (732):  the battle at which an army of Franks turned back the Moslems a few miles from Paris.  Afterwards, the invaders were driven back across the Pyrenees.  Tours marked the greatest penetration of Islam into western Europe.
Charles Martel ["the Hammer"]:  the Frankish commander who won the battle.
Within a century, Islam had spread from France to India; however, after the defense of Constantinople and the Battle of Tours, which came within 15 years of one another, it became clear that Islamic expansion had, for a time, run out of steam.
Factor accounting for the end the first wave of Arab expansion:
(1)  Overextension of the Arab population
(2)  The reappearance of old divisions and hostilities among the people who had converted to Islam
(3)  Birth of the Sunnite-Shiite split within Islam
For a time, traditional enemies had submerged their old hostility in their religious zeal.  In the early days of any new religion, this is a common phenomenon.  However, as the initial enthusiasm wore off, the old hostilities reemerged.  Moslems began fighting Moslems; and the monolithic structure of Islam, which had been so important in its expansion, broke down.
In addition to these old hostilities, Islam actually gave rise to some new divisions - the most important of which was the split between Sunnites (Sunni) and Shiites (Shia).
Caliph:  "Successor to the Prophet"; highest religious and political figure in Islam.
Sunnite:  this was the 'liberal' wing of Islam.  It believed:
(1)  The office of caliph should be open to all good Moslems; and should be filled as democratically as possible, in a manner similar to the primitive tribal democracy which had long existed among the Arabs.
(2)  Moslems, in seeking religious truth, should heed not only the Koran, but also some of the other early writings of Islam (including the Sunna, from which the Sunnites take their name).
Shiite:  the 'fundamentalist' wing of Islam.  It believed:
(1)  The office of caliph should be reserved for members of Mohammed's family (the monarchical principle).
(2)  Moslems should heed only the Koran in religious matters.
The Succession Crisis:  When Mohammed died, he had only a daughter, Fatimah.  As a result, he was succeeded by his father-in-law, Abu Bekr, who became the first caliph.  When Abu Bekr died two years later [634], a major lieutenant of Mohammed, Omar, became the second caliph.  Since he was not a member of Mohammed's family, the Shiites were dissatisfied.  When Omar's son succeeded him as the third caliph, Shiites assassinated him and rose up against his family in what has become known as the War of the Camel.  This began a long-lasting struggle between the two groups for control of the Islamic world, with first one and then the other seizing temporary advantage.
The first great ruling families of Islam reflect the split:
(1)  Ommiad Dynasty [Sunnite] with political capital at Damascus [661-750]
(2)  Abbasid Dynasty [Shiite] with political capital at Bagdad [750-1258]
Each shift in the balance of power tended to produce breakaway regions which would not acknowledge the change.  The most prominent example is Islamic Spain, a frontier province that supplies a microcosm of the divisions that descended upon Islam.  When the Ommiad Dynasty was overthrown in 750, and most of its members were slaughtered, the last survivor, Abd al Rahman, fled to Spain where he set up an Ommiad Emirate of Cordoba hostile to the new Abbasid caliphate at Baghdad.  Eventually, this emirate became the caliphate of Cordoba.  In Spain, tensions persisted between Sunni Arabs, Shiite Arabs, and North African Berbers.
By the 8th century, Baghdad had become the leading Islamic city in the world, the only real rival to Constantinople in Europe or the Near East.  However, Mecca always remained the religious capital.
Although the Abbasid Dynasty survived into the 13th century, by the 11th century, the Arabs were losing power to a new group of invaders, a people coming into the Near East from central Asia known as the Turks.  The arrival of the first wave, the Seljuk Turks, would lead to those western invasions of the Near East known as the Crusades.