America
In Central America dating back to 2,500BC we have record of two types of dogs. One was a medium sized dog somewhat like a wolf which was reared for food and ritual sacrificial purposes. Interestingly, the other was a small dog with a globular shaped head that appeared to be kept as a companion, probably the predecessor of the modern Chihuahua[2].
When the first civilization in central and north America developed in about 1200 BC in the coastal regions of the southern part of the Gulf of Mexico[1] we have America's first companion dogs.
References and Further Reading
[1] Gascoigne, Bamber. “History of Mexico” HistoryWorld. From 2001, ongoing.http://www.historyworld.net
[2] Fernand Mery 'the Life, History and Magic of the Dog' Published 1970 by Madison Square Press, Grosset & Dunlap Inc. New York 10010, Library of Congress Catalog Card No:78-117172 Chapter 2 Page 35