Each of these monsters is uniquely defined by a Species (which gives it its basic form and abilities) and a sub-type (which defines its color scheme, modifies its appearance, and slightly alters some of its statistical capabilities). This combination, called a Breed, is a reliable way to categorize monsters because of the inconsistency of name and design for any given monster between the games. For example, Golem/Suezo indicates a monster with species Golem, sub-type Suezo, and manifests as a large, humanoid figure with the bright yellow skin and a single eye that are characteristic of the Suezo monster species.
Each monster species also has at least one "unknown" breed. These breeds cannot be created by combining, because their sub-type is unknown. They can only be unlocked directly at the Shrine. For example, in Monster Rancher 2, inserting the Monster Rancher 1 disc creates a rare breed of Suezo called "Sueki Suezo", which has an unknown sub-type. All unknown breeds are notated as Species/???.
According to the story presented at the start of Monster Rancher 2, the monsters were created by God in response to a series of natural disasters humans found themselves incapable of dealing with properly. Once monster use became commonplace, the humans turned them into weapons of war. To limit these problems, God sealed the monsters into the disc-shaped stones called saucer stones. An untold amount of time later, the Tochikan tribe (introduced in Monster Rancher 3) discovered the method for unsealing the monsters. However, due to their xenophobic nature, they refused to share this technology until after the events of Monster Rancher 3 had ended.
Within the storyline of the anime, after their creation monsters were developed through genetic engineering as designer pets, until a war broke out in which the monsters were modified into biological weapons that could have their physical forms stored on discs. One tribe in particular, the Pendant tribe, made the most powerful monster of all. Soon, however, the monsters began to fight back, and although the ensuing conflict destroyed much of the world's civilization and technology, later generations used the discs (now called Mystery Discs because they could not tell what was inside) to revive the monsters to be used as pets and beasts of burden, and created a sport in which they were used as competitive fighters.
All items (2014)