Why does Mongolia have a very low population density?

"The country's low population can be explained in part by its geographic and climatic extremes: Mongolia is home to soaring mountains and burning deserts, including the Gobi Desert in the southern third of the country; because of the country's high average altitude, winters are long and temperatures extreme." http://www.nationsencyclopedia.com/economies/Asia-and-the-Pacific/Mongolia.html