The Great Plains has more railways than the Himalayan Mountains. Why?

The distribution pattern of the railway network in the country has been influenced by physiographic, economic and administrative factors. Level land of the great plains of India, with high density of population and rich agriculture and greater industrial activity, have favoured development of railways in these areas. Flood plains of Bihar and Assam, and the rugged topography of the Himalayan region, have very few railway lines. Sparsely populated sandy deserts of Rajasthan and hilly tracts of the Sahyadri are unfavourable for the development of railways.