Many petroglyphs, rock art, are thought to represent some kind of symbolic or ritual language.

Pictures, rock art, from Vitlycke, Aspeberget, Fossum and Jörlov - Massleberg, Sweden
The rock art, petroglyphs, is an outstanding example of Bronze Age art, ca 1800 - 600 BC.

The oldest rock art, carvings, petroglyphs, are dated to Neolithic and late Upper Paleolithic boundary, about 10,000 to 12,000 years ago.
Around 7,000 to 9,000 years ago other writing systems, such as pictographs and ideograms, began to appear.
Rock carvings have been found in all parts of the world except Antarctica, with highest concentrations in parts of Africa, Scandinavia, Siberia, North America and Australia.

There are many theories to explain their purpose. Rock carvings are often thought to be astronomical markers, maps, or other forms of symbolic communication.
They might also have been a by-product of other rituals. Sites in India have been identified as musical instruments or rock gongs.

Rock art, carvings probably had deep cultural and religious significance for the societies that created them.
Many rock carvings are thought to represent some kind of not-yet-fully understood symbolic or ritual language. Later carvings from the Nordic Bronze Age in Scandinavia seem to refer to some form of territorial boundary between tribes, in addition to possible religious meanings. The Siberian carvings almost look like some early form of runes, although there is not thought to be any relationship between them.