Mongolia is known as the country of "Blue Sky." It can be divided into four natural zones: mountain-forest steppe, mountain steppe and, in the extreme south, semi-desert and desert. It is 1,564,116 square kilometers and is slightly smaller than Alaska. For centuries, Mongolian herders and their families have roamed the grasslands following their animals, building, packing, and rebuilding their traditional gers, or tents, to make their living from nature’s bounty. The herder diet relies heavily on meat and dairy products, The meat-dependent diet arises from the need for hearty food to stave off the cold and long winters. The size of the livestock holdings of most families, particularly newcomers who have migrated from urban centers, is well below the subsistence level. For a sustainable livelihood over the long term, a family of herders needs at least 10 heads of cattle or yak or 70 sheep. Climate change and Overgrazing is also threatening the herder’s way of life by degrading their scarce natural resources. Up to 30 percent of Mongolia’s grassland biomass production has been lost over the past 40 years.