What was one characteristic unique to olmec culture?

One characteristic unique to Olmec culture is that they produced stone heads of colossal size. These were carved in Basalt and all of them display unique facial feature so that they can be  considered portraits of actual  rulers. The heads can be nearly 3 meters high and 8 tons in weight, and the stone from which they were carved was in some cases transported 80 km or more using huge balsa river rafts.

They also liked to mix animals to create wonderful creatures  such as were-jaguars, a cross between a human and a jaguar, which may have been their supreme deity. It is known  they also liked to drink chocolate.

possible the invasion of room could have been avodiable but the people of rome were to stubboron and to wealthy the kingdoms saw them as a threat if they dialred it downa   bit ten i dont think they wouldnt failed   china was not iacvvdoaible they caused war to much and were out of hand therefor that must have happened india i dont really know it could of