The order Artiodactyla is defined as "hoofed mammals with even-numbered toes". It's a very successful group of animals and is represented on almost every continent i the world, and in all kind of climates. The order of Artiodactyla is included in the infraorder Ungulates, which holds all hoofed mammals. 

The infraorder Ungulates (hoofed mammals) holds some smaller orders besides the Artiodactyla. Among those are the Oddtoed Mammals (Perissodactyla) - as the Zebras and Rhinos, and the really small orders of Elephants (Proboscidea), and  - Dassies (Hyracoidea).

If you are really interested in the systematics of these animals, visit this site: Artiodactyla