Bilad al-Sham was first organized into the four ajnad (military districts; singular jund) of Dimashq (Damascus), Hims (Homs), al-Urdunn (Jordan), and Filastin (Palestine), between 637 and 640 by Caliph Umar following the Muslim conquest.

As centralized Abbasid rule over Bilad al-Sham collapsed in the 10th century, control over the region was divided by several potentates and the ajnad only represented nominal divisions.

[1][2] It was so named from the perspective of the people of the Hejaz (western Arabia), who considered themselves to be facing the rising sun, that the Syrian region was positioned to their left, while to their right was al-Yaman ("the right-hand-region").

[8] The goal of the Muslims at the start of the conquest was likely bringing the Arabic-speaking nomadic, semi-nomadic, and settled tribesmen of the southern Syrian desert fringes under their control.

[8] Under Khalid's supreme command, the Muslim armies besieged and captured the southern Syrian urban centers of Bosra, Damascus, Beisan (Scythopolis), Pella, Gaza, and temporarily, Homs (Emesa) and Baalbek (Hierapolis).

[10] In the third phase, beginning about 637, the Muslim armies quickly occupied the northern Syrian countryside, while steadily conquering individual towns throughout the region whose garrisons held out alone following the breakdown of the imperial defense.

[11] As governor, Mu'awiya, forged strong ties with the old-established Arab tribes of Syria, which, by dint of their long service under the Byzantines, were more politically experienced than the tribesmen of Arabia, who filled the ranks of the Muslim armies.

[12] The tribes and commanders of Syria backed Mu'awiya in his confrontation with Caliph Ali at the Battle of Siffin in 657, which ended in a stalemate and an agreement to arbitrate their dispute.

The Meccan leader of the revolt, Ibn al-Zubayr, was recognized as caliph across much of the Muslim empire, while Yazid I's son and successor, Mu'awiya II, succumbed to the plague.

Under his son and successor, Abd al-Malik (r. 685–705), Syrian troops reconquered the rest of the Caliphate and killed Ibn al-Zubayr in a second siege of Mecca.

Abd al-Malik inaugurated a more Arab–Islamic government in Syria by changing the language of its bureaucracy from Greek to Arabic, switching from Byzantine coinage to a strictly Islamic currency, and building the Dome of the Rock in Jerusalem, which he may have promoted as an additional center of Muslim pilgrimage to Mecca.

[15] Abd al-Malik's son and successor, al-Walid I (r. 705–715), ruled with autocratic tendencies and less tolerance for the non-Muslims in Syria and the empire in general, which reached its greatest territorial extent during his reign.

During his rule and that of his successors, Damascus retained its role as the administrative capital of the empire, but the caliphs increasingly resided in their country estates in the Syrian steppe.

The mainly Arab Syrians were marginalized by Iranian and Turkish forces who rose to power under the Abbasids, a trend which also expressed itself on a cultural level.

[20] From there he personally oversaw the distribution of allowances (ata) and rations (rizq) to the Muslim soldiery, tax collection from the conquered population, and the appointments to military command.

[22] The change of Muslim military objectives following Yarmouk, when focus shifted to the northern Syrian and Mediterranean fronts, also necessitated the establishment of additional army headquarters and garrisons, such as Homs, diminishing Jabiya's centrality.

By establishing the ajnad, Umar transformed the military structures into provincial governments concerned with the taxation of the local populations and the distribution of collected money and supplies for the troops.

[27][28] The separation may have been a response to the influx of northern Arab (Qays and Mudar) immigrant tribesmen to Qinnasrin and the Jazira during Mu'awiya's governorship and caliphate.

[29] According to the historian Hugh N. Kennedy, the separation was done at the request of Muhammad ibn Marwan, Abd al-Malik's brother and his commander responsible for the Jazira.

It spanned the frontier zone with the Byzantine Empire, extending from the areas immediately south of Antioch, Aleppo, and Manbij and eastward to the Euphrates.

[30][31] Jund al-Awasim served as the second defensive line behind the actual frontier zone, the Thughur, which encompassed the far northern Syrian towns of Baghras, Bayas, Duluk, Alexandretta, Cyrrhus, Ra'ban and Tizin.

The administrative system continued to be officially recognized by the Abbasid and Fatimid governments until the Crusader conquests of the western parts of Bilad al-Sham, beginning in 1099.

As a geographic expression, "Bilad al-Sham" continued to be used by Arabic-speaking Muslims into the late 19th century, when Suriyya, the Arabic word for "Syria", generally replaced the term in common usage.