The new-born creed soon showed its strongly militant character. Led by Khālid, a pillar of Islām who won by his prowess the title of the Sword of God, the Arabs defeated a Roman army with heavy loss, and took Damascus. In six years the whole of Syria and Palestine passed under their sway. Persia was the next object of attack. The Zoroastrians struggled long and desperately for their independence, but in 639 they suffered a crushing defeat at Nahāvend, a battle which must rank high amongst those which have influenced the current of the world's history. Yezdijerd, the last of the Sāsānian dynasty, fled through Sistān and Khorasan to Merv. Here he found no safe asylum, for the governor sent news of his arrival to the Turks, and the Khākān advanced in person to seize so rich a prize. The fugitive became aware of the intended treachery, and concealed himself in a mill near the city. The owner received him with apparent kindness, but was tempted by the splendour of the king's accoutrements to kill him while he slept. He severed Yezdijerd's head from his body, which he cast into the mill stream.1

The immediate results of the battle of Nahāvend were disastrous to civilisation. Persia was traversed in all directions by bands of marauding Arabs, and the miserable inhabitants suffered as severely as they had suffered at the hands of the Mazdakites. "The Caliph Othman," writes Gibbon,3 "promised the government of Khorāsān to the first general who should enter that large and populous country, the kingdom of the ancient Bactrians. The condition was accepted, the prize was deserved; the

1 The outraged hospitality was avenged, for the murderer was torn to pieces by the mob, while the body of Yezdijerd was embalmed and buried in his ancestral tomb at Istakhr.

* He was the Prophet's son-in-law, and had been elected in A.H. 44 by a council of six as successor to the stern 'Omar, the second Caliph.

3 Decline and Fall of the Roman Empire, chap. li.

standard of Mahomet was planted on the walls of Herāt, Merou, and Balkh; and the successful leader neither halted nor reposed till his foaming cavalry had tasted the waters of the Oxus." The ill-cemented power of the Caliph was more adapted for conquest than assimilation, and its area overrun by his undisciplined hordes was too vast to be held in permanent subjection. Conscious of their weakness, the Arabs spared no efforts to spread the tenets of Islam, which alone was capable of welding together communities differing widely in race, language, and customs. From this epoch dates the decline of the creed of Zoroaster throughout Persia and the countries of Central Asia. The assassination of the Caliph 'Omar by a Persian slave was the signal for a general insurrection throughout this loosely knitted empire. This was not finally quelled till A.H. 31 (652), when Ibn 'Amir gained a victory over the Persians at Khwārazm on the Oxus, and compelled the country as far as Balkh to acknowledge the Caliph's suzerainty. In A.H. 41 (661) 'Abdullah ibn 'Amir organised a successful expedition into Khorāsān and Sīstān; and in the course of the following year Kays ibn al-Haytham was sent thither as provincial governor. He was superseded in A.H. 43 (663) by 'Abdullah ibn Khāzim. In A.H. 45 (665) Ziyad, whom in the preceding year the officially recognised as his of Basra and "the East." Ghifarī was sent in A.H. 47 (667) on an expedition into

Great Caliph Mo'awiya had brother, was made governor Al-Hakam ibn 'Amir al

1 Cf. Muir, Decline and Fall of the Caliphate, p. 208.

Tabari, Annales, Series II. p. 15. From this date until the appearance in Central Asia of Kutayba in A. H. 86, our history is little more than an enumeration of Arab governors in Khorasan, whose rule was usually as uneventful as it was shortlived. We have, however, considered it fitting to enter here into detail somewhat disproportionate to the rest of our narrative, seeing that the facts have hitherto been only accessible in works of Oriental writers.

Khorasan. He occupied Tokhāristan and the country south and south-east of Balkh as far as the Hindu Kush, and was, moreover, the first Arabian general to cross the Oxus.1 Al-Hakam died at Merv in A.H. 50 (670), on his return from an expedition against the people of Mount Ashall.2 In the following year Rabi ibn Ziyād3 elHārithi was sent to Khorāsān to succeed him.* About this date many Arabs migrated with their families to Khorāsān and settled there.5 Rabi's first care was the reduction of Balkh, which had been the scene of a revolt, and this he effected without resorting to force. He also engaged the Turks in Kūhistan, and put them to rout. Among the fugitives was Nizak Tarkhun, who perished later at the hands of Kutayba ibn Muslim. Rabi also crossed the Oxus, but made no conquests on the farther side. His death, and that of his master Ziyād, took place in A.H. 53 (673). He named his son 'Abdullah as his successor, but the latter died two months later, and was succeeded by Khulayd ibn 'Abdullah el-Hanafi. On the death of Ziyad the Caliph gave the governments of Kūfa, Basra, and Khorāsān to his own son 'Ubaydullah, while he appointed Ziyad's son 'Ubaydullah, in supersession of Khulayd, as his lieutenant in Khorasan. 'Ubaydullah ibn Ziyad collected an army in Irāk, entered Khorāsān and, crossing the Oxus, penetrated into the mountains of Bokhārā,R and conquered Rāmtīna and half of Bay

1 Müller, Der Islam, i. p. 354

2 Tabari, Annales, II. p. 109.

3 He was not the son of the famous governor of Basra.

* In the interim the post seems to have been filled for a short time by Khulayd ibn 'Abdullah el-Hanafi (Tabari, II. p. 155).

5 Tabari, II. p. 156.

6 Vambéry considers Tarkhān (or Tarkhūn) to be an old Turkish title, which Mohammedan authors have regarded erroneously as a proper name. 7 Tabari, II. p. 156.

8 Tabari, II. p. 169. Tabari says he was the first to cross the mountains of Bokhārā on a camel, loc. cit.