ROCKY MOUNTAIN MEDICAL ASSOCIATION. 29 
tory, which it is beHeved may, to some extent, account 
for the great migratory movements supposed to have 
taken place in ancient times, and which may have as- 
sisted in populating the North American continent."^ 
* In connection with the theory that a portion at least of the popu- 
lation of America existing at the time of the discovery by Columbus 
w as derived from the Old World, and especially from Asia, it is worthy 
of remark that the several periods of the arrival of the Toltecs, 
Chichemecas, Acolhuans or Tezcucans, and Aztecs, in the valley of 
Mexico, and of the Incas in Peru, have a singular correspondence 
with some prominent epochs in Asiatic history. Wars and political 
convulsions have been the most frequent cause of great emigrations ; 
and while we have no positive proof that the revolutions of Asia have 
had any influences on the population of America, a curious coincidence 
of dates invites to an inquiry of the possible connection between the 
two continents in the Pre-Columbian Period. 
China and Tartary were subjected to great intestine commotions, ex- 
tending from A. D. 420 to A. D. 618, and resulting, according to the 
Chinese annals, in great emigrations from the empire. The Toltecs, 
the first known to us, and apparently the most civilized of all the tribes 
that occupied the valley of Mexico, made their appearance in that re- 
gion about A. D. 648. 
The conquest of Hindustan by Mahmoud of Ghazni, about A. D. 
1000, with its accompaniment of religious and political persecution, 
is known to have caused a great exodus of the Hindu population from 
their native land and their dispersion over the islands of the Eastern 
Seas. Not long afterward, about A. D. IC2I, appeared near the 
Lake of Titicaca, in Peru, Manco Capac, the founder of the dynasty 
and of the Empire of the Incas, whose religious observances and po- 
litical institutions bear strong resemblances to those of the Solar Race 
of Hindustan. 
Again, the conquest of Northern China by the Mantchu Tartars 
(A. D. 1 1 15), and the subversion of that ancient empire by the great 
Mongolian Chiefs, Genghis Khan and Octal Khan, A. D. 1234- 
'96, may not have been entirely unconnected with the advent of the 
Chichemecas (A. D. 1170), the Acolhuans (A. D. 1200), and the 
Aztecs (A. D. 1325), in the valley of Anahuac. That the Moham- 
medan and Tartar invasions of Eastern Asia were productive of great 
commotions in that region is very certain ; but it is probably impossible 
/ 
