 A cooperative venture between the Zoological Society of London and Mongolian scientists has resulted in successful reintroduction of these horses from zoos into their natural habitat in Mongolia; and , an estimated total of almost 400 horses existed in three free-ranging populations in the wild.In 2001, Przewalski's horses were reintroduced into the Kalamaili Nature Reserve in Xinjiang, China.There are also free-range populations living in large enclosures at several sites, and from 1998 a population has lived in the unenclosed Chernobyl Exclusion Zone, where with the absence of humans it is thought to be increasing in size.