[14] By the end of the 6th century, the Umayyads dominated the Quraysh's increasingly prosperous trade networks with Syria and developed economic and military alliances with the nomadic Arab tribes that controlled the northern and central Arabian desert expanses, affording the clan a degree of political power in the region.

[35] He had the surplus taxes from the wealthy provinces of Kufa and Egypt forwarded to the treasury in Medina, which he used at his personal disposal, frequently disbursing its funds and war booty to his Umayyad relatives.

[34][38] The first challenge to his authority came from the Qurayshite leaders al-Zubayr and Talha, who had opposed Uthman's empowerment of the Umayyad clan but feared that their own influence and the power of the Quraysh, in general, would dissipate under Ali.

[39][40] Backed by one of Muhammad's wives, A'isha, they attempted to rally support against Ali among the troops of Basra, prompting the caliph to leave for Iraq's other garrison town, Kufa, where he could better confront his challengers.

[42] Although Ali was able to replace Uthman's governors in Egypt and Iraq with relative ease, Mu'awiya had developed a solid power-base and an effective military against the Byzantines from the Arab tribes of Syria.

[52] The long-established, formerly Christian Arab tribes in Syria, having been integrated into the military of the Byzantine Empire and their Ghassanid client kings, were "more accustomed to order and obedience" than their Iraqi counterparts, according to the historian Julius Wellhausen.

[54] Mu'awiya preoccupied his core Syrian troops in nearly annual or bi-annual land and sea raids against Byzantium, which provided them with battlefield experience and war spoils, but secured no permanent territorial gains.

[55] Toward the end of his reign the caliph entered a thirty-year truce with Byzantine emperor Constantine IV (r. 668–685),[56] obliging the Umayyads to pay the Empire an annual tribute of gold, horses and slaves.

[62] Afterward, Ziyad launched a concerted campaign to firmly establish Arab rule in the vast Khurasan region east of Iran and restart the Muslim conquests in the surrounding areas.

[63] Meanwhile, Amr ibn al-As ruled Egypt from the provincial capital of Fustat as a virtual partner of Mu'awiya until his death in 663, after which loyalist governors were appointed and the province became a practical appendage of Syria.

Although it stymied active opposition to Yazid in Iraq, the killing of Muhammad's grandson left many Muslims outraged and significantly increased Kufan hostility toward the Umayyads and sympathy for the family of Ali.

[80] Al-Dahhak in Damascus, the Qays tribes in Qinnasrin (northern Syria) and the Jazira, the Judham in Palestine, and the Ansar and South Arabians of Homs all opted to recognize Ibn al-Zubayr.

[95][84] In 694 Abd al-Malik combined both cities as a single province under the governorship of al-Hajjaj, who oversaw the suppression of the Kharijite revolts in Iraq and Iran by 698 and was subsequently given authority over the rest of the eastern caliphate.

[115][117][116] In Damascus, Abd al-Malik's son and successor al-Walid I (r. 705–715) confiscated the cathedral of St. John the Baptist and founded the Great Mosque in its place as a "symbol of the political supremacy and moral prestige of Islam", according to historian Nikita Elisséeff.

[118] Noting al-Walid's awareness of architecture's propaganda value, historian Robert Hillenbrand calls the Damascus mosque a "victory monument" intended as a "visible statement of Muslim supremacy and permanence".

[128] Kairouan was firmly secured as a launchpad for later conquests, while the port town of Tunis was founded and equipped with an arsenal on Abd al-Malik's orders to establish a strong Arab fleet.

[126] His successor in Ifriqiya, Musa ibn Nusayr, subjugated the Berbers of the Hawwara, Zenata and Kutama confederations and advanced into the Maghreb (western North Africa), conquering Tangier and Sus in 708/709.

[131] Despite the distance from the Arab garrison towns of Khurasan, the unfavorable terrain and climate and his enemies' numerical superiority,[132] Qutayba, through his persistent raids, gained the surrender of Bukhara in 706–709, Khwarazm and Samarkand in 711–712 and Farghana in 713.

Nevertheless, the goal of conquering Constantinople was effectively abandoned, and the frontier between the two empires stabilized along the line of the Taurus and Anti-Taurus Mountains, over which both sides continued to launch regular raids and counter-raids during the next centuries.

Since avoidance of taxation incentivized both mass conversions to Islam and abandonment of land for migration to the garrison cities, it put a strain on tax revenues, especially in Egypt, Iraq and Khurasan.

[156] Thus, "the Umayyad rulers had a vested interest in preventing the conquered peoples from accepting Islam or forcing them to continue paying those taxes from which they claimed exemption as Muslims", according to Hawting.

From the caliphate's north-western African bases, a series of raids on coastal areas of the Visigothic Kingdom paved the way to the permanent occupation of most of Iberia by the Umayyads (starting in 711), and on into south-eastern Gaul (last stronghold at Narbonne in 759).

Al-Walid is reported to have been more interested in earthly pleasures than in religion, a reputation that may be confirmed by the decoration of the so-called "desert palaces" (including Qusayr Amra and Khirbat al-Mafjar) that have been attributed to him.

As the central power of the Umayyad rulers waned in the later years of the dynasty, some governors neglected to send the extra tax revenue to Damascus and created great personal fortunes.

[173] The Umayyad Syrian forces specialised in close order infantry warfare, and favoured using a kneeling spear wall formation in battle, probably as a result of their encounters with Roman armies.

[177][179] Some "Arab-Sasanian" coins dated between 692 and 696, associated with the mints in Iraq under governor Bishr ibn Marwan, stopped using the Sasanian image of the fire altar and replaced it with three male figures standing in Arab dress.

On the pattern of the Byzantine system, the Umayyads reformed their army organization in general and divided it into five corps: the centre, two wings, vanguards, and rearguards, following the same formation while on the march or on a battlefield.

[183] As a matter of fact, Umar II was reported to have said in one of his letters commanding not to "destroy a synagogue or a church or temple of fire worshippers (meaning the Zoroastrians) as long as they have reconciled with and agreed upon with the Muslims".

"[202] The Umayyads have met with a largely negative reception from later Islamic historians, who have accused them of promoting a kingship (mulk, a term with connotations of tyranny) instead of a true caliphate (khilafa).

"[203] In fact, it was precisely this class of scholars, based largely in Iraq, that was responsible for collecting and recording the traditions that form the primary source material for the history of the Umayyad period.