The same process with the same geographical character has been going on in the Sahara, as the French since 1890 have been expanding southward from the foot of the Atlas Mountains in Algeria toward Timbuctoo at the cost of the nomad Tuaregs. Territory is first subdued and administered by the military till it is fully pacified. Then it is handed over to the civil government. Hence the advancing frontier consists of a military zone of administration, with a civil zone behind it, and a weaker wavering zone of exploration and scout work before it.[337] Lord Curzon in his Romanes lecture describes the northwest frontier of India as just such a three-ply border. [Sidenote: Economic factors in expanding frontiers.] The untouched resources of such new countries tempt to the widespread superficial exploitation, which finds its geographical expression in a broad, dilating frontier. Here the man-dust which is to form the future political planet is thinly disseminated, swept outward by a centrifugal force. Furthermore, the absence of natural barriers which might block this movement, the presence of open plains and river highways to facilitate it, and the predominance of harsh conditions of climate or soil rendering necessary a savage, extensive exploitation of the slender resources, often combine still further to widen the frontier zone. This was the case in French Canada and till recent decades in Siberia, where intense cold and abundant river highways stimulated the fur trade to the practical exclusion of all other activities, and substituted for the closely grouped, sedentary farmers with their growing families the wide-ranging trader with his Indian or Tunguse wife and his half-breed offspring. Under harsh climatic conditions, the fur trade alone afforded those large profits which every infant colony must command in order to survive; and the fur trade meant a wide frontier zone of scattered posts amid a prevailing wilderness. The French in particular, by the possession of the St. Lawrence and Mississippi rivers, the greatest systems in America, were lured into the danger of excessive expansion, attenuated their ethnic element, and failed to raise the economic status of their wide border district, which could therefore offer only slight resistance to the spread of solid English settlement.[338] Yet more recently, the chief weakness of the Russians in Siberia and Manchuria--apart from the corruption of the national government--was the weakness of a too remote and too sparsely populated frontier, and of a people whose inner development had not kept pace with their rate of expansion. [Sidenote: Value of barrier boundaries.]