The legendary Annapurna region is the most diverse and popular trekking area in Nepal.  The Annapurna chain of mountains lies inland, causing a large area including Manang and Mustang to fall in the rain shadow, where the ideal time for trekking is during the monsoon as there is no rainfall and temperatures are moderate in these areas.

These parts are considerably drier than the southern slopes of the mountains. This leads to an arid landscape that is desert-like and very different from regions lower down where there are green pastures and fertile farmland.