The Olmec Cascajal Block
900 BCE
The Cascajal Block is a serpentinite tablet bearing 62 symbols that represent the oldest known writing in the Americas, dating to approximately 900 BCE. It predates the previously oldest known Mesoamerican writing by 400 years. The symbols appear in a linear sequence consistent with a true writing system, but the script has not been deciphered. It confirms that the Olmec — the 'mother civilisation' of Mesoamerica — had writing.