The "X-ray" tradition in Aboriginal rock art is thought to have developed around 2000 B.C. and continues to the present day. As its name implies, the X-ray style depicts animals or human figures in which the internal organs and bone structures are clearly visible.

X-ray art includes sacred images of ancestral supernatural beings as well as secular works depicting fish and animals that were important food sources. In many instances, the paintings show fish and game species from the local area.

X-ray paintings occur primarily in the shallow caves and rock shelters in the western part of Arnhem Land in northern Australia. Recently, a vast wall of more than 1500 Aboriginal rock art paintings has been found by archaeologists in north eastern Arnheim land.

The paintings in the Djulirri rock shelter in the Wellington Range chronicle Aboriginal contact with Maccassan traders from Sulawesi, and Europeans from the early sail ship days right through to WWII.

As James Woodford observes:

Contrary to the popular view that indigenous Australians were isolated on their island continent, waves of other seafaring visitors arrived long before British settlement. For hundreds of years there may have been an export economy in northern Australia driven by the Chinese appetite for trepang, or sea cucumber.While it has long been known that Macassans traded with Aboriginal people, the accepted date for this was in the early 18th century. The team of scientists believes it may have begun centuries earlier