The Siberian Tiger, also called the Amur tiger, Manchurian tiger, Korean tiger, and Ussurian tiger (depending on the region where individuals were observed), is a population (previously subspecies Panthera tigris altaica) of the Mainland Asian tiger (Panthera tigris tigris) in the Russian Far East and Northeast China, and possibly North Korea. It once ranged throughout the Korean Peninsula, north China, Russian Far East, and eastern Mongolia. Today, this population inhabits mainly the Sikhote Alin mountain region in southwest Primorye Province in the Russian Far East.
In 2005, there were 331–393 adult and subadult Siberian tigers in this region, with a breeding adult population of about 250 individuals. The population had been stable for more than a decade due to intensive conservation efforts, but partial surveys conducted after 2005 indicate that the Russian tiger population was declining. An initial census held in 2015 indicated that the Siberian tiger population had increased to 480–540 individuals in the Russian Far East, including 100 cubs. This was followed up by a more detailed census which revealed there was a total population of 562 wild Siberian tigers in Russia. As of 2014, about 35 individuals were estimated to range in the international border area between Russia and China.
The Siberian tiger is genetically close to the Caspian tiger of Central and Western Asia. Results of a phylogeographic study comparing mitochondrial DNA from Caspian tigers and living tiger subspecies indicate that the common ancestor of the Siberian and Caspian tigers colonized Central Asia from eastern China, via the Gansu−Silk Road corridor, and then subsequently traversed Siberia eastward to establish the Siberian tiger population in the Russian Far East. The Caspian and Siberian tiger populations were the northernmost in mainland Asia.