PREFACE. XXV 
tury B. c.,during which the peoples of an area as large as Europe, driven by 
nature from their home lands, drenched the soil of Asia and Europe with 
blood, gave dynasties to China, and overthrew the Greek and Roman 
Empires, recasting the whole racial and social complexion of the world? 
The home of our Aryan ancestors was then—in the sixties—thought 
by such authorities as Lassen and Max Miiller to have been in High Asia. 
Reading these speculations, I recalled the fact that on a native map in an 
old Chinese commentary of the historical book of Confucius, there was the 
legend at a point in the Tarim basin: ‘‘ Here dwell the Usun, a people with 
blue eyes and red hair.’’ And with this the problem assumed an added 
fascination. 
The reader who know seven the elements of the Aryan problem of 
fifty years ago will understand how quickly it became a controlling factor 
in my dream. ‘To the idea that the progressive shrinkage of an inland sea 
indicated a progressive desiccation that forced destructive radial migrations 
was added the thought that migrations similarly forced might have brought 
to Europe the Aryan peoples, Aryan culture, and Aryan languages. In this 
form the dream remained for many years the background of a busy life 
until 1891, when, in discussing it with the Director of the Russian Geological 
Survey, Mr. Tschernyscheff, I learned that strata containing shells of the 
glacial period had actually been found in a position that seemed to really 
point to an inland sea of that period. Then my dream assumed the form 
of what seemed to me a legitimate hypothesis, worthy of being tested. It 
had before this been too subjective in character. 
Among the friends with whom I had talked on the subject in the early 
eighties, Messrs. Henry Adams and Alexander Agassiz had given me much 
encouragement. So, after Mr. Carnegie had founded the Institution for 
scientific research that bears his honored name, I suggested to Mr. Agassiz, 
who was a Trustee, that the Institution should send an expedition to Central 
Asia to reconnoiter. This the Executive Committee agreed to do, on the 
condition that I should go myself. 
It is one thing for a man of scientific training to live in the enjoyment 
of framing an attractive but only subjectively supported hypothesis, and it 
is a quite different thing to find himself, as I then found myself, face to face 
with the duty of testing it on the ground. Fortunately for the enterprise, 
Professor W. M. Davis was sufficiently interested to volunteer, at my request, 
to take charge of the physical-geographical part of the reconnaissance. I 
had little doubt that Mr. Davis would find evidence toward confirmation of 
the physical side of the hypothesis; but it was not without much anxiety 
that I faced the uncertainties of a search for traces of long-since-vanished 
peoples and cultures, which, even if once existent, might well have been 
_ obliterated. 
