The Codex Maru was written by the people of the Kingdom of Maru, an ancient civilization that vanished long before the Kingdom of Avalor was born. The Codex contains the most ancient and powerful magic ever known. It was by using the magic found in the Codex that the Amulet of Avalor and the Scepter of Light were both created. It was later discovered by the Avalorans in the Maruvian ruins Avalor was founded in. When the Kingdom of Avalor was established, it was given to Avalor's first Royal Sorcerer and has been passed down to each new Royal Sorcerer ever since.
- The Codex was inspired by codices from the Mayan and Aztec civilizations.