Central Asia hosts grassland and desert regions that are globally important to nature conservation and local livelihoods. Several major vegetation surveys have been published on the region, with the majority focussing on areas within central Mongolia and north-eastern China. Much less information is available on plant community composition on the Dzungarian Basin, which forms a transitional zone between Central and Middle Asia in terms of flora. The Altai Mountains extend along the northern and eastern boundaries of the basin and intro-duce further environmental heterogeneity. For the present study, we assess horizontal and vertical gradients in plant community composition in both the Chinese and Mongolian parts of the Dzungarian Basin and the adjacent Altai Mountains. We show that steep environmental gradients trigger notable differences in plant community composition over relatively short distances. The study is based on data collected over three different sampling periods in the Mongolian part: In 2003, we sampled 208 plots; in 2010, 152 plots; and during the vegetation periods of 2012–2014, 280 plots. On the Chinese side, 58 samples were taken in 2013. Sample sites were deliberately chosen to represent relevant vegetation types, ranging from those of the high mountains to the lower oases. We collected biomass and mixed topsoil samples for soil analysis and compiled additional environmental data. A vegetation map was then pre-pared based on the supervised classification of remote sensing imagery. Our results reveal that four different main vegetation types (forest-steppe, steppe, desert and oasis) encom-pass twenty-one plant communities, with each type showing a clear altitudinal distribution, except for that at oases. Detrended Correspondence Analysis revealed the expected close correlation between altitude and species composition and productivity, but it also highlighted significant differences between the vegetation of neigh-bouring mountain ranges in the Chinese and Mongolian Altai.