The results of these expanded journeys opened a new era for the study of Central Asian geography as well as studies of the fauna and flora of this immense region that were relatively unknown to his Western contemporaries. Among other things, he described Przewalski's horse and Przewalski's gazelle, which were both named after him. He also described what was then considered to be a wild population of Bactrian camel. In the 21st century, the Wild Bactrian camel was shown to be a separate species from the domestic Bactrian camel. Przhevalsky's writings include five major books written in Russian and two English translations: Mongolia, the Tangut Country, and the Solitudes of Northern Tibet (1875) and From Kulja, Across the Tian Shan to Lob-Nor (1879). The Royal Geographical Society awarded him their Founder's Gold Medal in 1879 for his work.