nd long before Genoa had become her powerful rival.[420]

{107}

Only a little later than this the brothers Nicolo and Maffeo Polo entered
upon their famous wanderings.[421] Leaving Constantinople in 1260, they
went by the Sea of Azov to Bokhara, and thence to the court of Kublai Khan,
penetrating China, and returning by way of Acre in 1269 with a commission
which required them to go back to China two years later. This time they
took with them Nicolo's son Marco, the historian of the journey, and went
across the plateau of Pamir; they spent about twenty years in China, and
came back by sea from China to Persia.

The ventures of the Poli were not long unique, however: the thirteenth
century had not closed before Roman missionaries and the merchant Petrus de
Lucolongo had penetrated China. Before 1350 the company of missionaries was
large, converts were numerous, churches and Franciscan convents had been
organized in the East, travelers were appealing for the truth of their
accounts to the "many" persons in Venice who had been in China,
Tsuan-chau-fu had a European merchant community, and Italian trade and
travel to China was a thing that occupied two chapters of a commercial
handbook.[422]

{108}

It is therefore reasonable to conclude that in the Middle Ages, as in the
time of Boethius, it was a simple matter for any inquiring scholar to
become acquainted with such numerals of the Orient as merchants may have
used for warehouse or price marks. And the fact that Gerbert seems to have
known only the forms of the simplest of these, not comprehending their full
significance, seems to prove that he picked them up in just this way.

Even if Gerbert did not bring his knowledge of the Oriental numerals from
Spain, he may easily have obtained them from the marks on merchant's goods,
had he been so inclined. Such knowledge was probably obtainable in various
parts of Italy, though as parts of mere mercantile knowledge the forms
might soon have been lost, it needing the pen of the scholar to preserve
them. Trade at this time was not stagnant. During the eleventh and twelfth
centuries the Slavs, for example, had very great commercial interests,
their trade reaching to Kiev and Novgorod, and thence to the East.
Constantinople was a great clearing-house of commerce with the Orient,[423]
and the Byzantine merchants must have been entirely familiar with the
various numerals of the Eastern peoples. In the eleventh century the
Itali