Today's Geo Quiz is about as big as it gets. We're looking for an area that makes up 10 percent of the Earth's land surface.

This vast region spans much of northern Asia and Russia. This landmass covers about 75 percent of Russia's territory. Yet it's home to 40 million people, or only about a third of Russia's population.

The Ural Mountains stand tall on its western border with vast stretches of frozen tundra extending all the way to the Pacific in the east. This wide open territory boasts the world's deepest freshwater lake Lake Baikal, a trans-continental railway, and it contains huge deposits of minerals and natural gas.

Lake Baikal

It's also home to thousands of species of migratory birds -- including one called a Chiffchaff that we'll tell you more about here...