It is easy to argue that, since there were the Asiatic steppes with the wild horses ready to hand in them, man was bound sooner or later to tame the horse and develop the characteristic culture of the nomad type.

Yes, but why did man tame the horse later rather than sooner?
And why did the American redskins never tame the bison, and adopt a pastoral life in their vast prairies?
Or why do modern black folk and white folk alike in Africa fail to utilize the elephant?
Is it because these things cannot be done, or because man has not found out how to do them?
When all allowances, however, are made for the exaggerations almost pardonable in a branch of science still engaged in pushing its way to the front, anthropo-geography remains a far-reaching method of historical study which the anthropologist has to learn how to use.
To put it crudely, he must learn how to work all the time with a map of the earth at his elbow.
First of all, let him imagine his world of man stationary.

Let him plot out in turn the distribution of heat, of moisture, of diseases, of vegetation, of food-animals, of the physical types of man, of density of population, of industries, of forms of government, of religions, of languages, and so on and so forth.

How far do these different distributions bear each other out?
He will find a number of things that go together in what will strike him as a natural way.
For instance, all along the equator, whether in Africa or South America or Borneo, he will find them knocking off work in the middle of the day in order to take a siesta.

On the other hand, other things will not agree so well.