What region is often referred to as “the roof of the world”?

Which region of Russia and northern Kazakhstan, whose name is derived from the Tatar term for “sleeping land,” is notorious for the length and severity of its winters?

Which region of northern India and southern Nepal, situated between the Yamuna and Brahmaputra rivers, is a former marshland whose name means “Moist Land” in the local language?

Which of these cities is located in a region known as the Najd?

Which of these ancient regions, located in Mesopotamia between the Tigris and Euphrates rivers, was the site of the earliest known civilization?