Contrary to what the name suggests, this breed did not get their start in Australia....
Rather, they were first bred on the US West Coast during the gold rush of the 1800s. Settlers were eager to have help herding sheep and cattle, and the breed evolved from mixing of Spanish dogs that could thrive at the high altitude of the Rocky Mountains. Their aggressive personalities grew out of managing herds spread across large geographic areas.
Australian Shepherd Dogs were originally knows as Spanish Shepherds and California Shepherds, among other names. The Australian name comes from the blue merle coat thats common in other bona fide Australian dogs. The American Kennel Club recognized the breed in 1991. They are frequently seen in movies and on TV, where their obedience and hard-working attitude are a good match for doing multiple scene takes and spending long days on the set.