The incidence of goitre among the people living in the Himalayan region was quite high. Why?

A lot of snow is experienced in Himalayas which leads to the leaching of iodine from the soil. The crops grown in a soil which is iodine deficient will lead to people consuming food with low dietary intake of iodine. This will result in development of iodine deficiency in people Himalayan people in the form of goitre.