Some emerged at their specific sites and stayed spiritually in that vicinity. Others came from somewhere else and went somewhere else. Many were shape changing, transformed from or into human beings or natural species, or into natural features such as rocks but all left something of their spiritual essence at the places noted in their stories. Australian Aboriginal mythologies have been characterised as "at one and the same time fragments of a catechism, a liturgical manual, a history of civilization, a geography textbook, and to a much smaller extent a manual of cosmography." There are 900 distinct Aboriginal groups across Australia, each distinguished by unique names usually identifying particular languages, dialects, or distinctive speech mannerisms. Each language was used for original myths, from which the distinctive words and names of individual myths derive. With so many distinct Aboriginal groups, languages, beliefs and practices, scholars cannot attempt to characterise, under a single heading, the full range and diversity of all myths being variously and continuously told, developed, elaborated, performed, and experienced by group members across the entire continent. Attempts to represent the different groupings in maps have varied widely. "The Encyclopaedia of Aboriginal Australia" nevertheless observes: "One intriguing feature [of Aboriginal Australian mythology] is the mixture of diversity and similarity in myths across the entire continent." The Council for Aboriginal Reconciliation's booklet, "Understanding Country", formally seeks to introduce non-indigenous Australians to Aboriginal perspectives on the environment. It makes the following generalisation about Aboriginal myths and mythology: ...they generally describe the journeys of ancestral beings, often giant animals or people, over what began as a featureless domain. Mountains, rivers, waterholes, animal and plant species, and other natural and cultural resources came into being as a result of events which took place during these Dreamtime journeys. Their existence in present-day landscapes is seen by many indigenous peoples as confirmation of their creation beliefs... The routes taken by the Creator Beings in their Dreamtime journeys across land and sea... link many sacred sites together in a web of Dreamtime tracks criss-crossing the country. Dreaming tracks can run for hundreds, even thousands of kilometres, from desert to the coast [and] may be shared by peoples in countries through which the tracks pass... Australian anthropologists willing to generalise suggest Aboriginal myths still being performed across Australia by Aboriginal peoples serve an important social function amongst their intended audiences: justifying the received ordering of their daily lives; helping shape peoples' ideas; and assisting to influence others' behaviour. In addition, such performance often continuously incorporates and "mythologises" historical events in the service of these social purposes in an otherwise rapidly changing modern world.