Basra, penetrate
into Ahwaz, Fars, Kerman, Sind, and thus reach India and China." Such
travelers, about 900 A.D., must necessarily have spread abroad a knowledge
of all number {102} systems used in recording prices or in the computations
of the market. There is an interesting witness to this movement, a
cruciform brooch now in the British Museum. It is English, certainly as
early as the eleventh century, but it is inlaid with a piece of paste on
which is the Mohammedan inscription, in Kufic characters, "There is no God
but God." How did such an inscription find its way, perhaps in the time of
Alcuin of York, to England? And if these Kufic characters reached there,
then why not the numeral forms as well?

Even in literature of the better class there appears now and then some
stray proof of the important fact that the great trade routes to the far
East were never closed for long, and that the customs and marks of trade
endured from generation to generation. The _Gulist[=a]n_ of the Persian
poet Sa`d[=i][403] contains such a passage:

"I met a merchant who owned one hundred and forty camels, and fifty slaves
and porters.... He answered to me: 'I want to carry sulphur of Persia to
China, which in that country, as I hear, bears a high price; and thence to
take Chinese ware to Roum; and from Roum to load up with brocades for Hind;
and so to trade Indian steel (_pulab_) to Halib. From Halib I will convey
its glass to Yeman, and carry the painted cloths of Yeman back to
Persia.'"[404] On the other hand, these men were not of the learned class,
nor would they preserve in treatises any knowledge that they might have,
although this knowledge would occasionally reach the ears of the learned as
bits of curious information.

{103}

There were also ambassadors passing back and forth from time to time,
between the East and the West, and in particular during the period when
these numerals probably began to enter Europe. Thus Charlemagne (c. 800)
sent emissaries to Bagdad just at the time of the opening of the
mathematical activity there.[405] And with such ambassadors must have gone
the adventurous scholar, inspired, as Alcuin says of Archbishop Albert of
York (766-780),[406] to seek the learning of other lands. Furthermore, the
Nestorian communities, established in Eastern Asia and in India at this
time, were favored both by the Persians and by their Mohammedan conquerors.
The Nestorian Patriarch of Syria, Timotheus (778-820), sent