"From the discovery of , we know that the once existed over a much larger range extending into Burma and northern Vietnam in the south, in China almost as far north as Beijing, the capital, and near Hong Kong and Shanghai in the east. Changes in climate reduced some of the panda's range, but in the twentieth century, the prime factor has been the rapid encroachment of the human population on the . As native forests have been logged or clear-cut for agriculture, suitable panda habitat has continued to shrink, until today it is confined to six mountain ranges running southwest from south of to south of along the eastern edge of the ."