Some idea as to when this musical intrusion occurred may be obtained from Chaloupka's chronology of the rock art of the Arnhem Land Plateau. While maintaining that a study of rock art can provide important insights into the prehistory of Australia, Chaloupka considers it possible to position art periods, phases and styles of the plateau region between 'time indices given by known climatological, geomorphological and archaeological data, and by zoological and botanical evidence'. In addition to introduced species the paintings documents new weapons, including a multiplicity of spear types and the spear thrower.
Boomerangs are conspicuous by their absence from post-estuarine paintings.
The development of the modern trumpet can be traced back over thousands of years. All the major civilisations of the past, produced trumpets although our knowledge of these instruments relies on contemporary illustrations. Most ancient trumpets were straight, hooked and had a long almost cylindrical tube and a slightly flaring bell. It is often difficult to make a distinction between primitive trumpets and horns, for in each case the sound is produced by the vibration of the players lips. Primitive trumpets are found in every continent and are usually associated with ceremony and tribal rituals.