428 THE OEIGIN OF TEADITION 



vegetation, especially in tropical countries, exert a profound 

 influence upon contact. 



Other features in the environment may be regarded rather as 

 facilitating contact. Rivers form great arteries of communication, 

 and it is remarkable how small a hindrance they are to contact. 

 Thus * Christopher Gist, exploring the Ohio in 1751, found a 

 Shawnee village situated on both sides of the river below the 

 mouth of the Scioto, with about a hundred houses on the north 

 bank and forty on the south. The small and unique nation of the 

 Mandan Indians were found by Lewis and Clarke near the northern 

 bend of the Missouri in 1864 in two groups of villages on opposite 

 sides of the river. They had previously in 1772 occupied nine 

 villages lower down the stream, two on the east bank and seven 

 on the west.' ^ Freshwater lakes, though not salt lakes, have 

 again been centres in which contact has been favoured, as was 

 the case in Switzerland at one period and also in Mexico and 

 Peru where the highest level of progress was reached in America. 



In considering any area there are certain general features of 

 importance quite apart from those which actually hinder or 

 facilitate contact. In the case of any area there is what we may 

 call its location, that is to say, its position relative to its surround- 

 ings. The position of any area in Africa with regard to its distance 

 from the north-eastern corner, through which contact with 

 inhabitants of other continents came about, is obviously of great 

 importance, and similarly is the distance of any one area from 

 the sea when navigation has been developed. To location we may 

 add diversity of features which brings about the contact between 

 different economic systems. This feature of diversity is chiefly 

 relevant when considering large areas ; and in this respect Europe 

 and Asia are far more favoured than America. 



Lastly, differences in language are a potent influence in hinder- 

 ing contact though they are rather evidences than causes of isola- 

 tion. When once established differences in language intensify the 

 isolation due to other causes. It may be observed in passing that, 

 contrary to what might be expected, the degree to which among 

 primitive races ' foreign ' languages are understood is considerable. 



Though in the first two periods the importance of the various 

 factors in hindering and facilitating contact has varied greatly, 

 it is sufficient, when taking a broad view, to bear the general 



' Seniple, Geographic Environment, p. 357. 



