the seventh century by Theophylactus Samocatta,
vii. 7. See Yule's _Cathay_, vol. i. pp. xlix., clxviii.]

[Sidenote: The Nestorians.]

In the fourth and following centuries, Nestorian missionaries were very
active in Asia, and not only made multitudes of converts and established
metropolitan sees in such places as Kashgar and Herat, but even found
their way into China. Their work forms an interesting though melancholy
chapter in history, but it does not seem to have done much toward making
Asia better known to Europe. As declared heretics, the Nestorians were
themselves almost entirely cut off from intercourse with European
Christians.

[Sidenote: Effects of the Saracen conquests.]

[Sidenote: Constantinople in the twelfth century.]

The immediate effect of the sudden rise of the vast Saracen empire, in
the seventh and eighth centuries, was to interpose a barrier to the
extension of intercourse between Europe and the Far East. Trade between
the eastern and western extremities of Asia went on more briskly than
ever, but it was for a long time exclusively in Mussulman hands. The
mediaeval Arabs were bold sailors, and not only visited Sumatra and Java,
but made their way to Canton. Upon the southern and middle routes the
Arab cities of Cairo and Bagdad became thriving centres of trade; but as
Spain and the whole of northern Africa were now Arab countries, most of
the trade between east and west was conducted within Mussulman
boundaries. Saracen cruisers prowled in the Mediterranean and sorely
harassed the Christian coasts. During the eighth, ninth, and tenth
centuries, Europe was more shut in upon herself than ever before or
since. In many respects these were especially the dark ages of
Europe,--the period of least comfort and least enlightenment since the
days of pre-Roman barbarism. But from this general statement
Constantinople should be in great measure excepted. The current of
mediaeval trade through the noble highway of the Dardanelles and the
Bosphorus was subject to fluctuations, but it was always great. The
city of the Byzantine emperors was before all things a commercial city,
like Venice in later days. Until the time of the Crusades Constantinople
was the centre of the Levant trade. The great northern route from Asia
remained available for commercial intercourse in this direction. Persian
and Armenian merchants sent their goods to Batoum, whence they were
shipped to Constantinople; and silk was b