The rhesus macaque (Macaca mulatta), is one of the best-known species of Old World monkeys. It is listed as Least Concern in the IUCN Red List of Threatened Species in view of its wide distribution, presumed large population, and its tolerance of a broad range of habitats. Native to South, Central and Southeast Asia, troops of Macaca mulatta inhabit a great variety of habitats from grasslands to arid and forested areas, but also close to human settlements.
A complete list of introduced species for even quite small areas of the world would be dauntingly long. Humans have introduced more different species to new environments than any single document can hope to record. This list is generally for established species with truly wild populations—not kept domestically or on ranches—that have been seen numerous times, and have breeding populations.
Old World monkeys are all simian primates. They are more closely related to the apes than they are to the New World monkeys.