Ideograms
Ideograms — conceptual image of an abstract idea — were used to communicate messages, whereby one meaning combined with another meaning form a new meaning. The earliest artifacts of this symbolic merging were found in Mesopotamia (modern Iraq) of the Sumerians .
The image below is a clay accounting tablet, inscribed with what is called protowriting. In protowriting one conceptual meaning combined with another conceptual meaning forms a new meaning. For example, in the image below there is one sheep and ten notches, which combined means ten sheep.