Nyctereutes (Greek: nyx, nykt- "night" + ereutēs "wanderer") is a genus of canid which includes only two extant species, both known as raccoon dogs: the common raccoon dog (Nyctereutes procyonoides) and the Japanese raccoon dog (Nyctereutes viverrinus). Nyctereutes first entered the fossil record 5.5 million years ago (Mya) in northern China. It was one of the earliest canines to arrive in the Old World. All but two species became extinct before the end of the Pleistocene. A study suggests that the evolution of Nyctereutes was influenced by environmental and climatic changes, such as the expansion and contraction of forests and the fluctuations of temperature and precipitation.