The conservation of old-growth forests has regained international attention because of their crucial role in mitigating climate change and in providing refuge areas for biodiversity. The problem, however, is which forests should be prioritized for preservation and what should be done to ensure that other forests evolve to resemble high-value forests. Many agree here that the reference state should serve as a benchmark and guide management so that the forests furthest from that state come closer to it. For the European montane belt, it is commonly admitted that the reference forest is a mature fir-beech forest (Abies alba Mill., Fagus sylvatica L.) with yew (Taxus baccata L.). Palaeoecological and archaeological records provide a longer temporal perspective to address issues of naturalness, maturity, and ancientness, and thus shed light on the gap between these forests and a near-natural (reference) state. Through the analysis of charcoals from soils and charcoal kiln platforms we have attempted to better characterize the Holocene trajectory and sub-recent dynamics of these forest formations in two mountain areas: the Romanian Carpathian and the French Pyrenees. Our results from 6 stands, 3 in each massif are consistent with post-glacial forest recolonization processes known on a regional scale and species successions that followed the last glacier retreat. The temporal depth provided by our study in two disjointed massifs reveals a common trajectory during the late Holocene where the establishment of the fir-beech mixed forest resulted from a close co-construction between the life history of tree species and the development of pre-industrial societies. Considering the high heritage value of these forests inherited from human-nature interaction, it deserves to be considered in its own right and as a reference to be reached and preserved in the European montane level.