50 THE SUCCESSIVE CULTURES AT ANAU. 
iron culture. It will be seen by a reference to plate 5 that the latter part of the 
period following the copper culture and represented by the “‘mixed”’ strata includes 
the time during which history tells us that the “Scyths’’ overran the Persian 
Empire, and it may not be unduly stretching the imagination to see in this racial 
movement an armed migration set in motion by the increasing desiccation over 
the great Transcaspian plains. 
It would seem that the city of Anau was founded by a new people. They 
made a different pottery and they used the system of irrigation that has continued 
down to the present time. Artificial irrigation was necessary to counteract arid 
climatic conditions. Our shafts at Ghiaur Kala show that artificial irrigation was 
used at about the same time on the oasis of Merv under the Sassanian rule. 
CHRONOLOGY. 
The greatest interest centers naturally in the problem of the age of these 
different cultures, and in their relation to the origin of Western civilization, if any 
such relations may be shown to exist. The wide geographical separation between 
Anau and the fields of western cultures, and the paucity of objects found by us 
that recall in a definite manner similarities to objects of external civilizations, 
surround the subject with the greatest obstacles. 
A working hypothesis based on a different line of reasoning gradually formed 
itself in my mind and is developed in the following pages. To begin with I assume: 
1st. That distinctive pottery, peculiar to a culture throughout our successively 
superimposed earth layers, is evidence of corresponding continuity of that culture. 
2d. That since it is a fact that throughout the lives of our sites at Anau the 
towns were built only of air-dried bricks, without stone foundations, the secular 
rate of growth of culture-strata can be taken as proximately uniform. 
3d. That two separate sites, whose cultures are characterized by entirely 
different and peculiar potteries, can not exist contemporaneously for centuries in 
close proximity to each other without such an interchange of pottery as would 
come to light during the excavation. 
This is applying to archeology simple rules of geological reasoning. We know 
the thickness of the strata of each of the cultures of the three neighboring sites, 
and we know the aggregate existing thickness of the cultures of all the sites. If 
we take the duration of each culture to be proportionate to the thickness of its 
accumulated strata, the duration of the entire series will be represented by the 
aggregate existing thickness of all the strata plus any culture-gaps between different 
cultures, and minus any overlaps of the cultures of the neighboring sites. Having 
the standing thickness of the different cultures, two additional factors are needed 
to convert the stratigraphic record into a chronological one: 
(a) The assignment of values to the observed four intervals that existed 
between the different cultures. 
(b) The rate of accumulation of the culture-strata. 
