Of all the continents it is Asia that arguably provides the most contrast and variety. Frenzied cities are the antithesis to ancient farming villages. There are deserts and jungles, mountains covered in snow, forests and rice paddies. All major religions find a home here - Buddhism, Hinduism, Christianity and Islam - and cultures mingle and mix into a fusion that can only be Asian.
With a continent this large, it is no surprise you can travel in any season. Summer is best for Mongolia and Tibet while spring and fall are optimal times for China, Japan, Central Asia, Nepal and Bhutan. India and South East Asia are best experienced between November and March.