Kamino was a planet located in the outer rim that home to a reclusive society of very sophisticated cloners. A water planet the only above ground city is the capital Tipoca City as the majority of the Kaminoans live in underwater inclosures similar to the Gungans. In the decades before the Clone Wars Jedi Master Sifo Dyas had visited the planet and petitioned the Kaminoans to create a grand army for the Republic to confront a threat, Sifo Dyas believed, could destroy the Republic. As a member of the Jedi Council Sifo Dyas realized his actions would carry severe consequences should the other Jedi find out. Luckily and unfortunately Master Dyas was murdered by his close personal friend and newly appointed Sith Lord, Count Dooku before any one in the Order could find out. At the behest of his Sith Master Dooku erased the location of the planet from the Jedi Temple Archives insuring that the Jedi would not find the clone army until the two Sith Lords were ready.
But it didn't take long for Obi-Wan Kenobi to figure it out and rediscovered the planet,which already produced a clone army for the Republic.