The historical distribution reconstructed based on ENMs indicates that the examined species experienced a significant expansion from LIG to LGM, with continuous distribution spanning the HHM region. The Himalayas exhibit less species richness compared to the Hengduan Mountains, but their flora are highly similar, suggesting the Himalayan vegetation is predominantly derived from adjacent migrations than in–situ radiation (Yu et al., 2020). Climatic oscillations resulted in massive species extinctions in the Himalayas, which subsequently led to a low rate of in–situ radiation but created vacant areas and niches for species migrating from the Hengduan Mountains. Over the past millions of years, there has been continuous biological interchange between the Hengduan Mountains and the Himalayas. And during periods of climate fluctuations, species migration from the Hengduan Mountains to the Himalayas occurred more frequently (Xing & Ree, 2017). The LGM was characterized by colder global temperatures and extensive ice sheets covering North America, Northern Europe, and Asia (Schneider von Deimling et al., 2006). During the LGM, numerous warm–adapted species became extinct or retreated to refugia, whereas this period provided favorable conditions for the expansion of alpine and arctic flora. Taking the experimental species as an example, a continuous high–suitability area was formed along the HHM corridor, facilitating the exchange and diffusion of species among the HHM. As the glacial periods ended and temperatures rose, their distribution ranges contracted back to higher latitudes and altitudes (Birks, 2008; Liu et al., 2023; Petit et al., 2008; Pu et al., 2024).