Middle Ages:
Muhammad‘s first interaction with the people and tribes of Syria was during the Invasion of Dumatul Jandal in July 626 where he ordered his followers to invade Duma, because Muhammad received intelligence that some tribes there were involved in highway robbery and preparing to attack Medina itself.
William Montgomery Watt claims that this was the most significant expedition Muhammad ordered at the time, even though it received little notice in the primary sources. Dumat Al-Jandal was 800 kilometers (500 mi) from Medina, and Watt says that there was no immediate threat to Muhammad, other than the possibility that his communications to Syria and supplies to Medina being interrupted. Watt says “It is tempting to suppose that Muhammad was already envisaging something of the expansion which took place after his death”, and that the rapid march of his troops must have “impressed all those who heard of it”.
William Muir also believes that the expedition was important as Muhammad followed by 1000 men reached the confines of Syria, where distant tribes had now learnt his name, while the political horizon of Muhammad was extended.
By AD 640, Syria was conquered by the Arab Rashidun army led by Khalid ibn al-Walid. In the mid-7th century, the Umayyad dynasty, then rulers of the empire, placed the capital of the empire in Damascus. The country’s power declined during later Umayyad rule; this was mainly due to totalitarianism, corruption and the resulting revolutions. The Umayyad dynasty was then overthrown in 750 by the Abbasid dynasty, which moved the capital of empire to Baghdad.
Arabic – made official under Umayyad rule – became the dominant language, replacing Greek and Aramaic of the Byzantine era. In 887, the Egypt-based Tulunids annexed Syria from the Abbasids, and were later replaced by once the Egypt-based Ikhshidids and still later by the Hamdanids originating in Aleppo founded by Sayf al-Dawla.
Sections of Syria were held by French, English, Italian and German overlords between 1098 and 1189 AD during the Crusades and were known collectively as the Crusader states among which the primary one in Syria was the Principality of Antioch. The coastal mountainous region was also occupied in part by the Nizari Ismailis, the so-called Assassins, who had intermittent confrontations and truces with the Crusader States. Later in history when “the Nizaris faced renewed Frankish hostilities, they received timely assistance from the Ayyubids.”
After a century of Seljuk rule, Syria was largely conquered (1175–1185) by the Kurdish liberator Salah ad-Din, founder of the Ayyubid dynasty of Egypt. Aleppo fell to the Mongols of Hulegu in January 1260, and Damascus in March, but then Hulegu was forced to break off his attack to return to China to deal with a succession dispute.
A few months later, the Mamluks arrived with an army from Egypt and defeated the Mongols in the Battle of Ain Jalut in Galilee. The Mamluk leader, Baibars, made Damascus a provincial capital. When he died, power was taken by Qalawun. In the meantime, an emir named Sunqur al-Ashqar had tried to declare himself ruler of Damascus, but he was defeated by Qalawun on 21 June 1280, and fled to northern Syria. Al-Ashqar, who had married a Mongol woman, appealed for help from the Mongols. The Mongols of the Ilkhanate took Aleppo in October 1280, but Qalawun persuaded Al-Ashqar to join him, and they fought against the Mongols on 29 October 1281, in the Second Battle of Homs, which was won by the Mamluks.