To reach the Tien Shan mountains from the Kyrgyz capital of Bishkek, you head east until you hit the shores of a vast freshwater lake called Issyk Kul, and then you turn southeast, in the direction of the Chinese border—a drive of about ten hours, if the weather is good and the roads are clear. The week I made the trip, last winter, in the company of a snow leopard scientist named Tanya Rosen, it took considerably longer. There was rain in Bishkek, and snow on the plains. Every 20 miles or so, we slowed to allow young shepherd boys, stooped like old shepherd men, to drive their sheep from one side of the ice-slick road to the other. In the distance, the mountains loomed.