1) language, including the script - the Mayan language and the script (the only in the new world!) were shared among the city-states
2) science - calendar (and its religious interpretation) mathematics and astronomy
3) art and architecture - despite being separate states, the remains from different city-states are very similar and the architecture and the art form is shared.
The rise of civilization was supported by the local ecology of well-watered soil, and by the network of transportation that was provided by the Coatzacoalcos River basin. This, in turn, triggered the rise of an elite class. The elite class generated the demand for the production of sophisticated luxury artifacts that define Olmec culture. They shared the language, the way the city-states were governed by the noble, used the same method of counting, admired the same gods and told the related myths, Same laws, and same style of clothes.
Scientists use the geologic time scale to illustrate the order in which events on Earth have happened. ... They used relative dating to divide Earth's past in several chunks of time when similar organisms were on Earth. Later, scientists used absolute dating to determine the actual number of years ago that events happened.
