Focusing on geographic and environmental factors, this article discusses recent recurring shifts in the mode of subsistence – from transhumant to sedentary pastoralism – observed among the Bakhtiaris of central Zagros. The article suggests that the evolutionary changes have been part of an adaptation strategy followed by Bakhtiari communities in the face of new environmental conditions in the highlands, the scarcity and dispersion of resources, the cultural and economic vulnerability of the transhumant populations vis-à-vis sedentary farmers and pastoralists, and general shifts in the subsistence structures and mechanisms. With the expansion of agricultural and industrial productive activities across the Bakhtiari heartland, transhumant populations are facing limitations in terms territory, movement, and access to resources as well as constant changes in the social, economic, and cultural milieus. These factors tend to encourage the settlement of transhumant populations in the southern Zagors area. In presenting its arguments, the article benefits from anthropological field research conducted in 2005 on two Bakhtiari clans of Malek-Mahmudi and Tat-Kheyri in Aligudarz and North Dezful respectively.