They were permitted to restore their Churches, but
not to build new ones; they were forbidden to bear
arms or ride a horse, save in case of necessity, and
they even then had to dismount on meeting a Moslem; they were subject to the usual poll-tax. Yet the Nestorians were the most powerful non-Moslem community while the Caliphs reigned at Bagdad (750-1258), and had a higher tradition of
civilization than their masters. They were used at
court as physicians, scribes, and secretaries, and
thus gained great influence, having much freedom
in canonical matters, elected Patriarchs, etc. The
Arab scholarship which came to Spain, and was a
great factor in mediaeval learning, begins in great
part with the Nestorians of Bagdad. They handed
on to their Arab masters the Greek culture which
was inherited in Syriac translations. So we find
the Caliphs treating them as chief of the Christian
communities, and at times civil authority over all
Christians had been given to the Nestorian Patriarch.
Early in the eleventh century Al-Biruni, a Moslem writer from Khiva, mentions the Nestorians as the most civilized of the Christian communities under the Caliph. He says that there are three sects of Christians Melchites, Nestorians and Jacobites. " The most numerous of them are the Melchites and Nestorians; because Greece and the adjacent countries are all inhabited by Melchites, whilst the majority of the inhabitants of Syria,
