Answer:
a complex writing system
Step-by-step explanation:
Olmecs were considered the first civilization that lived in the ancient Mexico. They were the first Mesoamerican people. They appeared in Mexico around 1600 BCE. Their cultures and social beliefs influenced many other civilization that flourished later.
They were considered to create a hieroglyphic writing system which is a complex writing system. Also developed calendar. They are famous for the immense stone heads that are made from the volcanic rocks. It all shaped the present picture of the Mexican landscape.