[Arab geneologists] offer[] a scheme of the subdivision of patriarchal tribes by which all Arabs who possess a nisba or gentile name can trace back their genealogy to one of two ultimate stocks, the Yemenite or S. Arab stock, whose great ancestor is Cahtan, and the Ishmaelite or N. Arab stock, whose ancestor is ‘Adnan, a descendant of Abraham through Ishmael. The latter stock bears also indifferently the names of Ma’add or Nizar, the former being represented as the son and the latter as the grandson of ‘Adnan.

W. Robertson Smith, Kinship & Marriage in Early Arabia 5 (1903).

Qays and Yaman are pre-Islamic tribes from the northern (Qays) and southern (Yaman) regions of the Arabian Peninsula who have a long history of mutual hostility and strife.
Qays, from the North, are descendants of Ismail. Also called: descendants of Adnan, Adaniyiin, Nizar, Nizariyya, Mudar, Mudariyya, Qaysiyya. Rabi’a tribe is usually included in this grouping because they were loyal to the Northerners, though technically they are descendants of Nizar, a Qaysi

Patricia Crone Were the Qays and Yemen of the Umayyad period political parties?. 71.1 Der Islam, 1-57. (1994)

Yaman, from the South, are descendants of Qahtan. Also called: ahl al-Yaman, al-Yamaniyya. The genealogists divide the Arabs  into sons of Ismail and sons of Qahtan, who are northerners and southerners respectively); and according to the historians, this division was of acute importance in the later Umayyad period, in which the two descent groups would behave as rivals and engage in asabiyya, ‘partisan behavior’.

Patricia Crone Were the Qays and Yemen of the Umayyad period political parties?. 71.1 Der Islam, 1,1 (1994)

In the Battle of Marj Rahit in 684 AD ( Syria ), Kalb (Yamani) defeated the Qays. The Qays/Yaman divide in Khurasan (Basra) was a “response to tensions exacerbated by the immigration of Azd (Yamani) from Oman.”

Patricia Crone Were the Qays and Yemen of the Umayyad period political parties?. 71.1 Der Islam, 1, 3 (1994)

At all events, as far as control of the most lucrative and prestigious provinces of the caliphate were concerned, that is Iraq and Khurasan, the Syrian Yemenis were doing badly in the competition; and since local troops related to their Syrian governors on the basis of descent, the Yemenis of Iraq and Khurasan were doing badly too. The Syrian Yemenis were responsible for garrison duties all over the empire, and above all in Iraq. Pace Shaban, there is no evidence that they resented this duty, what they resented being rather that they did not have undisputed control of this province. They did rule Iraq for a full fifteeen years under Khalid al-Qasri (a very long time in view of the short tenures that most governors enjoyed), but they lost control of it again when Khalid was dismissed in favour of yet another member of al-Hajjaj’s family, who was unwisely allowed by al-Walid II to torture Khalid al-Qasri to death). It was against this background that the Yamaniyya planned their coup, which obviously was not meant to end their role as imperial troops, but rather to give them control of the Syrian metropolis in which the highest decisions, including those affecting the allocation of Iraq, were made. Whatever their intentions, there certainly is no doubt that the events of 744 amounted to a military coup. The generals who had so far governed the provinces now took over the capital as well, and though the Yamaniyya were to be ousted, first by Marwan II and next by the Hashimiyya, the men who ousted them were generals too.

Patricia Crone Were the Qays and Yemen of the Umayyad period political parties?. 71.1 Der Islam, 1, 55-57 (1994)
Map of Ummayad Syria
Map of Ummayad Syria, from Fowden, Garth. Qusayr ‘Amra: Art and Umayyad Elite in Late Antique Syria. Berkeley (Calif.): University of California Press, 2004.¨*

Internally, the unity of the Umayyad Empire was threatened by several phenomena, the most important being the rise of tribal factionalism. Although scholars disagree over whether the terms “Qays” and “Yaman” refer to tribal considerations, political parties, or interest groups, it is generally accepted that the Qays stood for the expansion of the empire and the exclusion of non-Arab clients, while the Yaman criticized the policy of expansion and advocated equal status for Arab Muslims and non-Arab converts to Islam. The accession of Sulayman, who had allied himself with the Yamanis while serving as governor of Palestine, signaled a shift in the balance of power away from Qaysis, as the new Caliph proceeded to dismiss the Qaysi governors appointed by his predecessors, replacing them with men from the Yaman. In distant Farghanah, the Qaysi commander, Qutayba b. Muslim al-Bahili, realizing that his political usefulness had come to an end, tried to raise a revolt against the new Calif, but his supporters, both Arab and non-Arab, turned against him, slew him, and returned to their homes. An effort to mollify tribal factionalism was made by ‘Umar II, who chose governors over whom he had control and whom he believed to be competent, irrespective of their tribal affiliations. This policy was short-lived, however, as ‘Umar reigned for only two years. Under his successor, Yazid II, who sought to reestablish the old order, the Qaysis returned to power, embittered by the humiliations they had suffered since the accession of Sulayman; they were determined to take revenge. It was during the caliphate of Yazid II, in the year 101/719-720, that Yazi b. al-Muhallab al-Azdi staged his revolt, an episode to which Tabari devotes considerable attention. Although this was not, strictly speaking, a tribal conflict — Ibn al-Muhallab’s own trip of the Azd sided against him — it nevertheless contributed to the intensification of the factional schism as Qaysis were installed in Iraq and the East in its aftermath. More than any other factor, these tribal rivalries, which spanned the entire empire, contributed to the downfall of the Umayyads.

D. S. Powers, The History of al-Tabari Vol. 24: The Empire in Transition: The Caliphates of Sulayman,’Umar, and Yazid xiv (SUNY Press 1989).

The Druze are Arabs and tribal in origin. They are divided between the Qays and Yaman, or northern and southern traditional family rivalries.

Spencer C. Tucker & Priscilla Roberts, eds. Druze. in Encyclopedia of the Arab-Israeli Conflict, The: A Political, Social, and Military History: A Political, Social, and Military History 306 (ABC-CLIO 2008).

The historical division between the two lines of genealogy engulfing most of the Arab population in Syria – that between the Northern tribes of Arabia (Qays) and the Southern (Yaman) – did not always determine the side taken by this or that tribe or clan, but added an important dimension to the whole strife.

David Kushner. “Zealous towns in nineteenth‐century Palestine.” 33.3 Middle Eastern Studies 597, 601 (1997).

The Bedouin were present in great numbers around the town and in Hebron itself. A large part of its population was, in fact, of nomadic stock, and the proximity of the desert, to the south and the east, facilitated the intervention of tribal units in whatever conflicts erupted. The division between Qays and Yaman was felt here no less than in Nablus.

David Kushner. “Zealous towns in nineteenth‐century Palestine.” 33.3 Middle Eastern Studies 597, 602 (1997).

According to the theory of the Arab genealogists the groups were all patriarchal tribes, formed, by subdivision of an original stock, on the system of kinship through male descents. A tribe was but a larger family; the tribal name was the name or nickname of the common ancestor. In process of time it broke up into two or more tribes, each embracing the descendants of one of the great ancestor’s sons and taking its name from him. These tribes were again divided and subdivided on the same principle, and so at length that extreme state of division was reached which we find in the peninsula at the time of the prophet. Between a nation, a tribe, a sept or sub-tribe, and a family there is no difference, on this theory, except in size and distance from the common ancestor. As time rolls on the sons of a household become heads of separate families, the families grow into septs, and finally the septs become great tribes or even nations embracing several tribes.

W. Robertson Smith, Kinship & Marriage in Early Arabia 3-4 (1903).

Whatever their vision, the Banū Umayya ibn ʿAbd Shams had better claims to Arab than to Muslim loyalties. As is well established, not only was Abū Sufyān long hostile and a late-comer to Islam, but in the course of the First and Second Fitnas, the Banū Umayya had alienated both the principals and the followers of major “faith-based” constituencies — the Ṣaḥāba, the Anṣār, and the ʿAlids. Both the Sufyānid victory in the First Fitna and the Marwānid Restoration of Umayyad rule in the Second Fitna were accomplished by force of arms against fellow Muslims and “Islam” — shedding Muslim blood and destroying the Kaʿba — an awkward base upon which to construct a claim for legitimate Islamic authority.
Clearly the Banū Umayya had to construct authority and legitimacy, and had to seek allies and supporters, where they could. In this respect the tribal range wars between the Qaysīs (Muḍar) and Kalbīs/Yamanīs in al-Jazīra (northern Mesopotamia) became absorbed into the struggle for the caliphate as the Yamanī faction, and with them the powerful Christian tribe of the Banū Taghlib, sided with the Banū Umayya while the Qaysī faction sided with the Zubayrids — most directly fighting for Muṣʿab ibn al-Zubayr in Iraq. As we shall see, this enmity and the concomitant bloodshed between the Banū Taghlib and especially the Qaysī tribe of the Banū Sulaym continued well after the pacification of Iraq and the various stages of incorporation of the Qaysī tribes into the Umayyad state.
The pertinent names and dates for our purposes are:
• 65/684: Umayyads recognize Marwān ibn al-Ḥakam as caliph.
• 1 Muḥarram 65/18 August 684: The final Battle Day of Marj Rāhiṭ, a plain north-west of Damascus: Marwān ibn al-Ḥakam is supported by the Kalbī/Yamanī tribes; al-Akhṭal’s tribe, the Banū Taghlib, have sided with them in support of the Umayyads. The Marwānids and their supporters inflict a decisive defeat upon al-Daḥḥāk ibn Qays al-Fihrī, the head of the Qaysī tribes, and supporter of the rival caliphate of ʿAbd Allāh ibn al-Zubayr. Al-Daḥḥāk is slain and his severed head presented to Marwān. Umayyad control of Syria is reestablished. Zufar ibn al-Ḥārith al-Kilābī
escapes and holds out in Qirqīsiyāʾ.
• 65/685: Marwān ibn al-Ḥakam dies and his son ʿAbd al-Malik accedes to the (shaky and highly contested) caliphate.
• 69/689: ʿAbd al-Malik makes a ten-year truce with the Byzantine emperor in return for annual tribute.
• 70/689: Yawm Tharthār at the al-Ḥashshāk River: the Banū Taghlib defeat the Qaysī
and pro-Muṣʿab ibn al-Zubayr tribe of the Banū Sulaym, slay its leader ʿUmayr ibn al-Ḥubāb, and send his severed head to ʿAbd al-Malik.
• 71/690–691: Defeat of Zufar ibn al-Ḥārith, the Qaysī supporter of Muṣʿab ibn al-Zubayr, at Qirqīsiyāʾ; he agrees to a negotiated truce with ʿAbd al-Malik.
• 72/691: Defeat of Muṣʿab ibn al-Zubayr in Iraq.
• 17 Jumādā I or II 73/4 October or 3 November 692: After a six-month siege of Mecca by the notorious general al-Ḥajjāj ibn Yūsuf, during which the city and even the Kaʿba were bombarded, ʿAbd Allāh ibn al-Zubayr is defeated and slain on the battlefield. ʿĀm al-Jamāʿa (Year of [Re]unification of the Community).
• 73/692: Yawm Bishr: al-Jaḥḥāf, leader of the Qaysī tribe of the Banū Sulaym, now Umayyad clients, massacres the Banū Taghlib.
• 73/692: ʿAbd al-Malik resumes wars with the Byzantines.
• 86/705: Death of ʿAbd al-Malik.

Suzanne Pinckney Stetkevych, “Al-Akhtal at the Court of ‘Abd al-Malik: The Qasida and the Construction of Umayyad Authority”, in Antoine Borrut & Fred M. Donner, ed., Late Antique and Medieval Islamic Near East 30-31 (Oriental Institute, University of Chicago 2016)