This is a description I found on the internet about the breed.
Serengeti Cat: Derived from Bengal x Oriental Shorthair cross, bred to create tall, golden cat with black spots that resemble African Serval but without using Servals or other wild species. (Other sources suggested Jungle Cat x Bengal but no information available on this cross.) Via the two founding breeds, the Serengeti contains genes from the Asian Leopard Cat, British Shorthair, domestic shorthair moggies, Indian Mau, Ocicat, Egyptian Mau, Abyssinian, and Burmese/Bombay, Siamese and even Persian. The Serengeti Cat was developed simultaneously in the USA and UK. American cats have larger ears than the UK breeds due to the ears inherited from the American Orientals. The allowable colours are as in the Bengal : Leopard Spotted and Snow Leopard, plus melanistic (Black Panther). See also Savannah (UK) for a Bengal x Siamese cross and Savannah (US) for a Serval x Domestic cross.
Here is another link with more info:
http://www.kingsmarkfarms.com/serengeti/history.html