While writing the post on mountain climate(s), I wanted to provide examples for the severity of living conditions in temperate mountains. I did the usual thing: I Googled “driven into the mountains” and found an amazingly large harvest of websites with that very wording, from around the world.

Here are some examples, but the web has many more:

• Near East: And the Amorites forced the children of Dan into the mountain: for they would not suffer them to come down to the valley (Source: Judges 1:34, King James translation, click here)
  

  The hypothetical Yeti, or Abominable Snowman would be yet another canditate of a species driven into the mountains… With the present inflation of human ancestors, no doubt that Propp’s followers could make the case! Primary source of figure: Hergés Tintin in Tibet. Secondary source: Penseurs himalayens, especially http://www.jabiru-blog.com/PHOTOS-12-09/herge-yeti.jpg. For Propp, see http://en.wikipedia.org/wiki/Propp

• Indonesia: The Mangyans are simple people. They were once coastal dwellers driven into the mountains to avoid religious conversion by the Spaniards, raids by Moro pirates, and the influx of recent migrants (Source: click here);
• Western Europe, UK: The Welsh call themselves Cymry, in the plural, and a Welshman Cymro, and their country Cymru, of which the adjective is Cymreig, and the name of their language Cymraeg. They are a branch of the Celtic family, and a relic of the earliest known population of England, driven into the mountains of Wales by the Anglo-Saxon invaders. (Source: click here)
• Japan: Japanese census takers, nosing around in the northern mountains of their country, discovered a village, unmentioned by maps, containing 152 inhabitants, none of whom had ever heard of the outside world. They wore clothes of a style fashionable in Japan centuries ago. Their teeth were blackened for beauty; they ate only fruit and vegetables. Archaeologists calculated that they must be descendants of a clan called Heike which was driven into the mountains in the 11th Century by Genji […]. (Source: click here.)
• Western Europe, Italy: After the Normans conquered Caltanissetta, the harems disappeared but the Muslims did not. They were driven into the mountains, and some converted […] (Source: click here.)
• Taiwan: […] it was not until the 6^th century CE that Chinese settlement began to occur. During this time, the aboriginal inhabitant were assimilated, killed, or driven into the mountains in the center of the country. (Source: click here.)
• Costa Rica: 2009 marked the three hundredth anniversary of the last great indigenous war of resistance in Costa Rica. Three hundred years ago, the inhabitants of Talamanca, the mountain range that separates Costa Rica and Panama, fought their last furious battle for freedom. Faced with the threat of slavery from both Hispanic colonists and English raiders; helpless to prevent and horrified to watch their children die of measles, smallpox, and other Old World diseases; driven into the mountains from their richest fishing and farming grounds; these desperate men and women struck one last blow for their autonomy and independence. (Source: click here.)
• Caucasus: At this point, the Russians started to refer to them as Ingush and Chechens. Chechens were driven into the mountains, while the Ingush were encouraged to settle on the plain. (Source: click here.)

If some populations had no option but move to the mountains, it is obvious that others took refuge there, or actually took advantage of the favourable mountain conditions! Examples are provided by D. Keys (see references of this post). Here is an rapid summary of Key’s book Catastrophe. It has been known that a major disruption of climate occurred world-wide around the mid  sixth century as a result of several major volcanic eruptions which injected large amounts of dust and aerosol into the atmopshere, shielding off sunshine and deeply modifiying atmospheric circulation. As usual, Wikipedia has the details. Keys’ theory is that the climatic conditions that derived from this worldwide volcanic winter lasted several years, and led to worldwide crop failures, famines and the first plague epidemic. The events did actually reset history and very deeply modified the political equilibria that had prevailed up to this time. Here is, for instance, a quote from his chapter 27 which deals with South America (Kindle loc.  3562-90):

The climatic events of the mid–sixth century—the drought and the El Niños—had the effect of destabilizing the Moche empire. The thirty-year drought must have led to severe famines, and the c. 556 El Niño flood would have destroyed irrigation systems, thus making the food supply situation even more precarious. The population, weakened by starvation, would then have fallen prey to a range of contagious diseases, much as the Teotihuacanos of Mexico were succumbing to famine and disease at exactly the same time. Although the entire Andean region was hit by the climatic problems, the already arid coastal plain was almost certainly affected more disastrously than the highland areas to the east. In times of drought, lowlands normally suffer worse than highland areas. Those few rain clouds that are around will tend to shed their load when they encounter mountain terrain. What is more, the reduced rainfall in the mountains is not sufficient to sustain the river volumes required to water coastal plains. The water-starved lowlands would have lost much of their vegetation cover, and the loss in turn would have reduced water retention, accelerated soil erosion, and encouraged the encroachment of desert terrain. Additionally, the large coastal plain populations had only two ecological niches to exploit for food—the flatlands and the sea. By contrast, highland peoples, with a variety of altitudinal zones at their disposal, had more options. They could exploit valley bottoms, mountain slopes, high mountain pastures, and even lakes. Even when the lakes shrank, they often actually assisted agriculture by revealing new, ultrafertile land. And of course all mountain peoples were, by definition, closer to key water sources. At first the change in geopolitical balance would probably have allowed foothill areas between the coastal plain and the highlands to break loose from Moche control. This would have made access to their food, copper, gold, and silver resources, as well as the ritually important drug crop coca, much more difficult for the Moche and much easier for the highland peoples, especially the most powerful highland group, the Huari. As the economic as well as geopolitical situation increasingly favored the mountain areas, the north-south highland trading trail would have become the key commercial highway in Peru—very much at the expense of the only other major north-south trail, the one that ran along the coast. Moreover, the coast soon began to suffer the bizarre secondary effects of drought and severe El Niño flooding. During the brief yet severe episodes of such flooding, millions of tons of sand were scoured out of the parched landscape, swept coastward by the El Niño torrents, and dumped immediately offshore. Long-shore drift then spread them out along the coast, while the tides swept them onto the beaches and strong coastal winds formed them into dunes and drove them inland. In classic dsert fashion, the dunes marched inland—well after the drought had ended—and destroyed agricultural land and even towns. Indeed, part of the Moche city around the Huaca del Sol was inundated by this tide of sand. Thus it was that this lethal cocktail of disasters affected the highland and coastal areas to quite different degrees, and the people of the relatively poor mountainous interior almost certainly suffered less than their ostentatiously rich, coastal-plain opposite numbers. Demographically and in terms of social organization and control, the coast no longer had an advantage. The Moche civilization appears to have fragmented politically, probably under pressure from highland peoples, especially the Huari.

The story which Keys tells is that mountain areas can also be very favourable, because they are wetter than the lowlands, and because they are characterised by a very large variety of ecological niches, which in turn provide conditions favourable to the development of biodiversity (the Mountain climate blog has some details). Tropical mountains tend thus to be home to sucessfull populations, which sometimes grow fast (as can be seen today in areas like the east African Highlands) and eventually over-exploit their natural resource base.

References

Keys, D. 1999. Catastrophe, an investigation into the origins of the modern world.  Balantine, 352 pp. The Kindle edition (the one I read!) appeared in October 2000.