Under al-Walid, the armies of the Caliphate "received a fresh impulse" and a "period of great conquests" began, according to historian Julius Wellhausen.
During the second half of his reign, the Umayyads reached their furthest territorial extent.
Expansion of the eastern frontier regions was overseen by al-Hajjaj from Iraq.
Without participating in person, he carefully chose, equipped and generously financed the commanders of the expeditions.

Al-Hajjaj's lieutenant governor of Khurasan, Qutayba ibn Muslim, launched numerous campaigns against Transoxiana (Central Asia), which had been a largely impenetrable region for earlier Muslim armies, between 705 and 715.
Despite the distance from the Arab garrison towns of Khurasan, the unfavorable terrain and climate and his enemies' numerical superiority, Qutayba, through his persistent raids, gained the surrender of Bukhara in 706–709, Khwarazm and Samarkand in 711–712 and Farghana in 713.
In contrast to most other Muslim conquests, he did not attempt to settle Arab Muslims in Transoxiana; instead, he secured Umayyad suzerainty through tributary alliances with local rulers, whose power remained intact.
The exceptions to this policy were the cities of Samarkand and Bukhara, which were each assigned Arab garrisons and tax administrators, had their Zoroastrian houses of worship razed and in the case of Samarkand, fitted with a mosque.
As a long-term result, both cities developed as future centers of Islamic and Arabic learning.
From 708/09, al-Hajjaj's nephew and lieutenant commander, Muhammad ibn Qasim, conquered Sind, the northwestern region of South Asia.

In the west, al-Walid's governor in Ifriqiya (central North Africa), Musa ibn Nusayr, a holdover from Abd al-Malik's reign, had subjugated the Berbers of the Hawwara, Zenata and Kutama confederations and proceeded with his advance toward the Maghreb (western North Africa).
In 708/09, he conquered Tangier and Sus, in the far north and south of modern-day Morocco, and installed his son Marwan as governor of the former and his Berber mawlā (freedman; pl.
mawālī), Tariq ibn Ziyad, as governor of Sus.
In the same year, Musa dispatched his son Abd Allah to raid the Balearic Islands.
Tariq invaded the Visigothic Kingdom of Hispania (Iberian Peninsula) in 711, and was reinforced by an army led by Musa in the following year.
By 716, a year after al-Walid's death, Hispania had been nearly entirely conquered.
The massive war spoils netted by the conquests of Transoxiana, Sind and Hispania were comparable to the amounts accrued in the early Muslim conquests during the reign of Caliph Umar ibn al-Khattab (r. 634–644).

Closer to the Umayyad seat of power in Syria, al-Walid appointed his half-brother Maslama governor of the Jazira (Upper Mesopotamia) and charged him with raiding the frontier zone with Byzantium.
Though Maslama established a strong power base in his province, he achieved few territorial gains.
After a lengthy siege, the Byzantine fortress of Tyana was captured in c. 708.
Al-Walid entrusted most of Syria's military district governorships to his sons; al-Abbas was assigned to Homs and fought reputably in the campaigns against Byzantium alongside Maslama, while Abd al-Aziz, who also took part in the anti-Byzantine war effort, and Umar were appointed to Damascus and Jordan, respectively.
Al-Walid did not participate in the campaigns and is reported to have left Syria once as caliph when he led the Hajj pilgrimage to Mecca in 710.
Under al-Walid, the armies of the Caliphate "received a fresh impulse" and a "period of great conquests" began, according to historian Julius Wellhausen. During the second half of his reign, the Umayyads reached their furthest territorial extent. Expansion of the eastern frontier regions was overseen by al-Hajjaj from Iraq. Without participating in person, he carefully chose, equipped and generously financed the commanders of the expeditions. 
Al-Hajjaj's lieutenant governor of Khurasan, Qutayba ibn Muslim, launched numerous campaigns against Transoxiana (Central Asia), which had been a largely impenetrable region for earlier Muslim armies, between 705 and 715. Despite the distance from the Arab garrison towns of Khurasan, the unfavorable terrain and climate and his enemies' numerical superiority, Qutayba, through his persistent raids, gained the surrender of Bukhara in 706–709, Khwarazm and Samarkand in 711–712 and Farghana in 713. In contrast to most other Muslim conquests, he did not attempt to settle Arab Muslims in Transoxiana; instead, he secured Umayyad suzerainty through tributary alliances with local rulers, whose power remained intact. The exceptions to this policy were the cities of Samarkand and Bukhara, which were each assigned Arab garrisons and tax administrators, had their Zoroastrian houses of worship razed and in the case of Samarkand, fitted with a mosque. As a long-term result, both cities developed as future centers of Islamic and Arabic learning. From 708/09, al-Hajjaj's nephew and lieutenant commander, Muhammad ibn Qasim, conquered Sind, the northwestern region of South Asia. 
In the west, al-Walid's governor in Ifriqiya (central North Africa), Musa ibn Nusayr, a holdover from Abd al-Malik's reign, had subjugated the Berbers of the Hawwara, Zenata and Kutama confederations and proceeded with his advance toward the Maghreb (western North Africa). In 708/09, he conquered Tangier and Sus, in the far north and south of modern-day Morocco, and installed his son Marwan as governor of the former and his Berber mawlā (freedman; pl. mawālī), Tariq ibn Ziyad, as governor of Sus. In the same year, Musa dispatched his son Abd Allah to raid the Balearic Islands. Tariq invaded the Visigothic Kingdom of Hispania (Iberian Peninsula) in 711, and was reinforced by an army led by Musa in the following year. By 716, a year after al-Walid's death, Hispania had been nearly entirely conquered. The massive war spoils netted by the conquests of Transoxiana, Sind and Hispania were comparable to the amounts accrued in the early Muslim conquests during the reign of Caliph Umar ibn al-Khattab (r. 634–644). 
Closer to the Umayyad seat of power in Syria, al-Walid appointed his half-brother Maslama governor of the Jazira (Upper Mesopotamia) and charged him with raiding the frontier zone with Byzantium. Though Maslama established a strong power base in his province, he achieved few territorial gains. After a lengthy siege, the Byzantine fortress of Tyana was captured in c. 708. Al-Walid entrusted most of Syria's military district governorships to his sons; al-Abbas was assigned to Homs and fought reputably in the campaigns against Byzantium alongside Maslama, while Abd al-Aziz, who also took part in the anti-Byzantine war effort, and Umar were appointed to Damascus and Jordan, respectively. Al-Walid did not participate in the campaigns and is reported to have left Syria once as caliph when he led the Hajj pilgrimage to Mecca in 710.
Al-Walid I