PEOPLEbe found in the vicinity of Basra in 656, and they occupied the open
country between Maysan and Khuzistan in the 680s.^94
In central Mesopotamia, the Arabs of Namir and Taghlib who were
driven permanently north of the Euphrates by the conquest survived
in the Diyar Rabi'a. Large numbers of the Taghlib and Namir joined
'Ali's army on his way from Kufa to the Battle of Siffin in 657.^95 The
T aghlib were the most important group of pastoral Arabs who re-
mained Christian by coming to terms with the Muslim Arabs. At first
the Taghlib objected to paying tribute in return for protection at the
time of the conquest because they considered it degrading. They crossed
the upper Euphrates and threatened to join the Byzantines until they
were excused from the payment of tribute, and each adult man or
woman of the tribe was allowed instead to pay double the tax paid
by Muslims. In return they agreed not to baptize their children and
not to prevent anyone in their tribe from converting to Islam. The
taxes assessed on the Taghlib were levied collectively on their camels,
sheep, cattle, and crops.96
Ziyad ibn I:Iudayr of the tribe of Asad, who was sent by 'Umar to
collect customs duties between Iraq and Syria, is said to have required
the T aghlib to pay twice the customs rate collected from Muslims. He
stretched a chain across the Euphrates and collected a two and one-
half percent ad valorem customs tax from Muslims, five percent from
protected non-Muslims, and ten percent from the unprotected. At first
he required the Taghlib to pay five percent of the value of their pos-
sessions each time they traveled in either direction. When a T aghlibi
merchant complained to 'Umar, he ordered Ziyad not to tax them
more than once each year.^97 Ziyad's activities not only suggest that
the former Byzantine-Sasanian border in upper Mesopotamia survived
the conquest as a place for collecting customs dues, but they also
indicate the continuing importance of Taghlibi merchants in the riv-
erine traffic between Iraq and Syria. The T aghlib also continued to
baptize their children and thereby, in 'Ali's opinion, forfeited their
rights to protection.^98
The Islamic conquest was not, in itself, a pastoralist migration. It
94 Tabari, Ta'rlkh, I, 3181; Il, 448.
95 Ya'qiibi, Ta'rlkh, Il, 218.
96 Abii Yiisuf, Khariij, pp. 100, 184--85; Baiadhuri, Futu!?, pp. 181-83; Qudama,
Khariij, p. 42; Yai)ya ibn Adam, Khariij, pp. 29, 55-56.
97 Abii Yiisuf, Khariij, pp. 185-86, 208-11; Ibn Sa'd, Tabaqiit, VI, 89; Yai)ya ibn
Adam, Khariij, pp. 55-56.
98 Yai)ya ibn Adam, Khariij, p. 55; Qudama, Khariij, p. 42.