Its status within the larger Pama-Nyungan family is disputed: though it shares some features, it also displays many innovative forms that are rare in other Australian languages, suggesting that it fits a distinctive typology.
They were in his view an inland people whose northern extension ran only as far as roughly the margins of the coastal plain some 40 miles (64 km) from the Gulf of Carpentaria's coastline.
The area concerned, now called the Port McArthur Tidal Wetlands System, lay around the Robinson and Wearyan rivers, and Leichhardt described emu traps around waterholes, fish traps and fishing weirs across rivers, well-used footpaths, major living areas with substantial dwellings, wells of clear water and a sophisticated method of detoxifying the otherwise extremely poisonous cycad nuts.
The pollution from the overflow of its washed ores has turned the nearby Hanrahan's Creek toxic and seeped over as far as the Wentworth Aggregation wetland, Wollogorang Station and affected sacred aboriginal sites such as Moonlight Falls.
An early survey of blood types suggested that the Garrwa had a high B phenotype ratio, a characteristic almost non-existent among Australian Aboriginal people, shared only by the Kaiadilt and Tagalag.