over Latin Christendom.[191] As the roads to Rome took the
pious wayfarers through Milan, Venice, Genoa, Florence, Bologna, and
other great cities of Italy, they were so many channels for the
distribution of Italian art and culture over the more untutored lands of
western Europe.

Though Mecca is visited annually by only seventy or eighty thousand
pilgrims, it puts into motion a far greater number over the whole
Mohammedan world, from westernmost Africa to Chinese Turkestan.[192]
Yearly a great pilgrimage, numbering in 1905 eighty thousand souls,
moves across Africa eastward through the Sudan on its way to the Red Sea
and Mecca. Many traders join the caravans of the devout both for
protection and profit, and the devout themselves travel with herds of
cattle to trade in on the way. The merchants are prone to drop out and
settle in any attractive country, and few get beyond the populous
markets of Wadai. The British and French governments in the Sudan aid
and protect these pilgrimages; they recognize them as a political force,
because they spread the story of the security and order of European
rule.[193] The markets of western Tibet, recently opened to Indian
merchants by the British expedition to Lhassa, promote intercourse
between the two countries especially because of the sacred lakes and
mountains in their vicinity, which are goals of pilgrimage alike to
Hindu and Tibetan Buddhist. They offer an opportunity to acquire merit
and profit at the same time, an irresistible combination to the needy,
pious Hindu. Therefore across the rugged passes of the Himalayas he
drives his yaks laden with English merchandise, an unconscious
instrument for the spread of English influence, English civilization and
the extension of the English market, as the Colonial Office well
understands.[194]

[Sidenote: Historical movement and race distribution.]

The forms which have been assumed by the historical movement are varied,
but all have contributed to the spread of man over the habitable globe.
The yellow, white and red races have become adapted to every zone; the
black race, whether in Africa, Australia or Melanesia, is confined
chiefly to the Tropics. A like conservatism as to habitat tends to
characterize all sub-races, peoples, and tribes of the human family. The
fact which strikes one in studying the migrations of these smaller
groups is their adherence each to a certain zone or heat belt defined by
certain isothermal lines (see