The first invasion
It began with the conquest of the Middle East. Byzantium lost the Levant, and the Sassanid state lost Mesopotamia.
The confrontation with Byzantium resulted in centuries-old Arab-Byzantine wars.
In 633-652, the Arabs defeated and subjugated Sassanian Iran.
In the years 641-642, the Arab conquest of Egypt took place by the warlord Amr ibn al-As.
In 643, with the siege of Derbent, the invasion of the territory corresponding to the modern mountain Dagestan began.
The first invasion of North Africa began in 647. After leaving Medina, 20,000 Arabs joined in Memphis (Egypt) with another 20,000 soldiers. Sheikh Abdullah ibn Saad commanded the Arabs. The Carthaginian Exarch Gregory declared the independence of his Exarchate from the Byzantine Empire. He gathered troops and fought with the Muslims, but was defeated in the battle of Sufetule (a city 220 km south of Carthage). After the death of Gregory, Carthage paid tribute to the Arabs. The campaign lasted another fifteen months, but in 648 Abdullah’s troops returned to Egypt. By 661, the Arabs seized all of Transcaucasia, as well as Derbent.
All Muslim conquests were soon interrupted by a civil war. This war was between rival Arab factions. The civil war began with the assassination of Caliph Uthman in 656, he was replaced by Ali ibn Abu Talib, who in turn was killed in 661. During this time, with the help of Byzantium and the Khazar Kaganate, many Transcaucasian countries withdrew from the Caliphate with the exception of Eastern Armenia.
Second invasion
After the civil war, the Arabs continued their conquests in North Africa. In 665, a new military invasion of the African Exarchate began. In 689, the new North African military campaign was over. The army of the Byzantine Greeks (30,000 soldiers) was defeated during this campaign. By the 40,000 Muslims who started this war, another 10,000 Arabs soon arrived, led by the Arab general Uqba ibn Nafi. Coming out of Damascus, the army passed through almost the whole of North Africa. In 670, the Arabs captured the city of Kairouan, rebuilt it, made it a strong fortress and the basis for further military action. This city became the capital of the Islamic region of Ifriqiya (the Arabic name of Tunisia). The fortress city covered the coastal areas of what is today Western Libya, Tunisia, and Eastern Algeria. After the settlement of Kairouan, the Arabs again continued the conquest of the Maghreb (the so-called Arabs of northwestern Africa). In the process of conquering the Maghreb, Uqba ibn Nafi captured the coastal city of Bugey and the modern city of Tangier. Both cities were once part of the Roman Mauretania.
But Ukba could not hold the conquered lands for a long time. In the rear of his army, a Berber rebellion broke out. Soon he was called back along with his army to suppress this uprising. In one of the battles against the Greek-African rebels, Ukba ibn Nafi was killed. In his place came the new commander Zuheir, but he also died in the fight against the rebels. Constantinople had already managed to send a large army to Africa.
Meanwhile, a new civil war broke out in Arabia and Syria. The conquest of the Arabs was again suspended.
The Third Invasion
In Asia, the Arabs were able to return the lost countries of the Caucasus. In 687, the Arabs took Kartli, Kakheti and Hereti – the three principalities of Eastern Georgia, but Kakheti and Hereti were at a favorable location, so the Arabs could not gain a foothold there. 10 years later, in 697, the Arabs moved to the west of Georgia. Governor Egrisi, the largest Byzantine-dependent state in Western Georgia, invited the Arabs to occupy the garrisons and expel the Greeks. However, in Western Georgia, for a long time, the Arabs entrenched only in Egrisi (this was due to the native tropical climate for the conquerors and strong garrisons and fortresses, as well as the central position of the country in Western Georgia): Abasgia and Apsilia (except for the southern one that belonged to Egrisi) were freed already in 711. The Chanet, on which the Arabs also encroached, remained in the sphere of influence of Byzantium. But anyway, by the year 700, the Arabs had seized all of Transcaucasia, with the exception of mountain Misiminii and Alanya, which was on the side of the Byzantine – Khazar alliance.
The new conquest of North Africa began with the Arabs retaking the cities of Ifriqiya. But Byzantium quickly redeployed troops from Constantinople. The Byzantines were joined by soldiers from Sicily and a strong contingent of Visigoths from Roman Spain. This forced the Arab army to retreat to Kairouan. The following spring, the Arabs launched a new offensive by sea and land. Soon they defeated the Byzantines and their allies at the battle of Carthage. In 698, the Arabs entered Carthage. Its stones served as material for the construction of the city of Tunisia. Another battle was fought near Utica, and the Arabs won again, forcing the Byzantines to leave North Africa. Five years passed before Hassan Ibn al-Numan, the new general of the Muslims, received new troops from the Caliphate. In the meantime, people in the cities of North Africa that had not yet been captured became angry at Berber domination. Thus, Hassan was welcomed on his return. In 709, the Arabs seized almost all of North Africa and divided it into three areas: Egypt with its governor in al-Fustat, the Maghrib (modern Morocco and Mauritania ) with the governor in Fez and Ifriqiya with its governor Musa ibn Nusayr.
Musa ibn Nusayr was a general. He was appointed governor of Ifriqiya and was responsible for the suppression of the renewed Berber uprising and the spread of Islam in the conquered lands. Musa and his two sons had 300,000 prisoners. Almost all the captives were sold into slavery and the proceeds from their sale went to the public treasury. Another 30,000 prisoners were forced to do military service. Musa also dealt with the constant raids of the Byzantine fleet. To fight, Musa built his own fleet. Moving deep into the Maghreb, his forces took Tangier in 709.
Sources:
Alfan, Louis. Great barbarian empires: from the Great Migration to the Turkic conquests of the XI century
Boris Sokolov. Arab conquests