The slaughter of Ḥusayn does not complete the tale of Yazíd's enormities. Medína, the Prophet's city, having expelled its Umayyad governor, was sacked by a Syrian army, while Mecca itself, where ‘Abdulláh b. Zubayr had set up as rival Caliph, was besieged, and the Ka‘ba laid in ruins. These outrages, shocking to Moslem sentiment, kindled a flame of rebellion. Ḥusayn was avenged by Mukhtár, who seized Kúfa and executed some three hundred of the guilty citizens, including the miscreant Shamir. His troops defeated and slew ‘Ubaydulláh b. Ziyád, but he himself was slain, not long afterwards, by Mus‘ab, the brother of Ibn Zubayr, and seven thousand of his followers were massacred in cold blood. On Yazíd's death (683) the Umayyad Empire threatened to fall to pieces. As a contemporary poet sang-- "Now loathed of all men is the Fury blind Which blazeth as a fire blown by the wind. They are split in sects: each province hath its own Commander of the Faithful, each its throne."[368] [Sidenote: Civil war renewed.] [Sidenote: Rivalry of Northern and Southern Arabs.] Fierce dissensions broke out among the Syrian Arabs, the backbone of the dynasty. The great tribal groups of Kalb and Qays, whose coalition had hitherto maintained the Umayyads in power, fought on opposite sides at Marj Ráhiṭ (684), the former for Marwán and the latter for Ibn Zubayr. Marwán's victory secured the allegiance of Syria, but henceforth Qays and Kalb were always at daggers drawn.[369] This was essentially a feud between the Northern and the Southern Arabs--a feud which rapidly extended and developed into a permanent racial enmity. They carried it with them to the farthest ends of the world, so that, for example, after the conquest of Spain precautions had to be taken against civil war by providing that Northerners and Southerners should not settle in the same districts. The literary history of this antagonism has been sketched by Dr. Goldziher with his wonted erudition and acumen.[370] Satire was, of course, the principal weapon of both sides. Here is a fragment by a Northern poet which belongs to the Umayyad period:-- "Negroes are better, when they name their sires, Than Qaḥṭán's sons,[371] the uncircumcisèd cowards: A folk whom thou mayst see, at war's outflame, More abject than a shoe to tread in baseness; Their women free to every lecher's lust, Their clients spoil for cavaliers and footmen."[372] Thus the Arab nation was again torn asunder by the old tribal pretensions which Muḥammad sought to abolish. That they ultimately proved fatal to the Umayyads is no matter for surprise; the sorely pressed dynasty was already tottering, its enemies were at its gates. By good fortune it produced at this crisis an exceptionally able and vigorous ruler, ‘Abdu ’l-Malik b. Marwán, who not only saved his house from destruction, but re-established its supremacy and inaugurated a more brilliant epoch than any that had gone before.