The Eurasian climates of today, 10 million and 30 million years ago are simulated using an atmospheric general circulation model that incorporates realistic continental geography and epicontinental sea distributions. The resulting climates compare well with various palaeoclimate records. The retreat of the Paratethys-an epicontinental sea-shifts the central Asian climate from temperate to continental conditions, and plays as important a role as uplift, of the Himalayan/Tibetan plateau in driving the Asian monsoon changes.