The origin of the Ninjago theme lies in the earlier Lego Ninja theme, which was released in 1988. This theme was based on Feudalistic Japan and featured ninjas, fortresses, catapults and horses. It originated in the Lego Castle theme that had been in existence since 1978. In 2000, Lego Ninja was replaced by Lego Knights. These themes eventually resulted in the introduction of the Ninjago theme, which included some of the original concepts of the Ninja theme, such as the dragons and fortresses, but also introduced modern day elements. The Ninjago theme then employed the use of an original story that would appeal to young teenage boys, by creating a cast of characters that focused on a group of ninja heroes and a wide variety of villains.
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