The uplift of the Tibet Plateau (TP) during the Miocene is crucial to understanding the evolution of Asian monsoon regimes and alpine biodiversity. However, the northern Tibet Plateau (NTP) remains poorly investigated. We use pollen records of montane conifers ( Tsuga , Podocarpus , Abies , and Picea ) as a new paleoaltimetry to construct two parallel midrange paleoelevation sequences in the NTP at 1332 ± 189 m and 433 ± 189 m, respectively, during the Middle Miocene [~15 million years ago (Ma)]. Both midranges increased rapidly to 3685 ± 87 m in the Late Miocene (~11 Ma) in the east, and to 3589 ± 62 m at ~7 Ma in the west. Our estimated rises in the east and west parts of the NTP during 15 to 7 Ma, together with data from other TP regions, indicate that during the Late Miocene the entire plateau may have reached a high elevation close to that of today, with consequent impacts on atmospheric precipitation and alpine biodiversity.

Significance: Palaeoecological analysis reveals that the expansion of rice agriculture in southern China and Southeast Asia around 2,000 y ago caused widespread deforestation and biodiversity changes in tropical and subtropical forests. Tropical forests, with the highest level of plant diversity and concentration of endemic species, suffered greater decline of arboreal richness than forests in subtropical and temperate areas. In subtropical ecosystems, total plant richness increased, despite arboreal decline, possibly thanks to the flourishing of herbs in an opening landscape. The disappearance of Glyptostrobus in southeastern Asia provides a case study as to how early rice agriculture endangered an endemic species by causing losses of its natural habitats, with prehistoric land-use changes leaving a clear legacy for today’s landscapes and species compositions.

Significance: Our study reveals a remarkable relationship between Late Holocene coastal evolution and the rise of rice agriculture across coastal Asia. Around 2,000 to 3,000 y ago, the emergence of coastal plains under freshwater conditions created expansive areas suitable for rice. We estimate that over the past three millennia the extent of coastal land suitable for wetland rice cultivation grew from about 16,000 km ² to 96,000 km ² . Intensive paddy field farming took hold rapidly as coastal landscapes changed. Thus, large-scale rice farming was not established in southern China and Southeast Asia until rather late in the Holocene. This model helps explain ancient DNA evidence suggesting a major Bronze Age demographic expansion of rice farmers of northern East Asian descent.