RELATION BETWEEN THE CLIMATIC CHANGES AND THE PREHISTORIC HUMAN MIGRATIONS DURING HOLOCENE BETWEEN GISSAR RANGES, PAMIR, HINDU KUSH AND KASHMIR. THE ARCHAEOLOGICAL AND ENVIRONMENTAL DATA
Résumé
The disappearance of the last hunters-gatherers established in mountainous Central Asia, the High Pamir since the beginning of Holocene (Osh Kona, 9580 + - 130 BP then 7145 + - 120 BP), then in the valleys of high and middle altitude (Gissar Range), asks the question of factors at the origin of their late extinction. Three missions of the Department of Prehistory of the National Museum of Natural History (Paris-France) were organized to identify the phenomenon. The presence of hunters-gatherers is attested later than 5000-4500 years BP in the high valley of Chitral (Yarkhun valley), in the border limit between Pakistan and Wakhan corridor which gives access to High Pamir (French mission of the Prehistoric Department, National Museum of Natural History, 1996, 1997, 1998)(figure 1). The human settlements of the tablelands (Pamir, Tibet) and of high valleys depend on multifactors, the complexity of which still remains to solve, because it is not enough to refer directly to the climatic fluctuations identified with the global warming. While the Indian subcontinent was exposed to increasing monsoons, between 8400 and 5500 years BP some of high valleys were isolated by accumulation of ice and snow in passes: the Nanga Parbat situated in the western extremity of the Himalayan chain, provoked climate asynchronisms. This massif exposed to the precipitations, offered the biggest known lowering (4500 metres) and provoked then accumulations of ice in sufficiency to compensate the melt of glacial fronts and snowed passes. This type of asynchronism is probably at the origin of the isolation of small populations of hunters-gatherers in High Pamir. Dispersal can be observed at about 2700 years BP in the direction of Southern valleys of Hindu Kush. Similarity between the Yarkhun techno - complexe (figure 2) known about the Cashmere and those discovered recently in the Siwaliks Frontal Range (Punjab, missions of the Department of Prehistory in India 2003, 2005, 2006 and on 2007) suggests migration routes towards Himalayan Piedmont (map). Nevertheless no explanation has been proposed to understand their fast extinction. A local event happened as attested by the drastic decrease of the biodiversity in the archaeological levels of Osh Kona; High Pamir now is a mineral desert. Those fast climate changes, a threshold maybe linked to recent global anthropic productions, can be correlated with increasing local warm effects such as the salinization of High Tibet lakes and Bostan Lake (Xinjiang).