Fig. 1. The Eurasian steppe biome.

a “Zonal steppe” denotes areas where the macroclimatically determined potential vegetation is steppes; their extent is based on Wesche et al.². “Extrazonal steppe” highlights areas where steppe outposts occur embedded in a matrix of forest vegetation (for details on delimitation of extrazonal steppe extent see Supplementary Methods). Shades of grey depict topography. b Distribution of major vegetation types⁷¹, extent of ice cover⁶² (white), and position of coastline⁶²(outline of vegetation layers) in western Eurasia at the Last Glacial Maximum, 20,000 years before present (BP). The underlying map depicts present-day Europe. Source data are provided as a Source Data file.