The language from the region known as Hunter River and Lake Macquarie to the north of Sydney is known from the work of the Rev Lancelot Threlkeld (1788-1859) who established a mission at Lake Macquarie between 1826 - 1841.

Threlkeld studied the language under the guidance of Biraban, also known as Johnny McGill, who later worked as an interpreter in court cases involving Aboriginal people.

Threlkeld's major descriptions of the language from the Hunter River and Lake Macquarie region published in 1834 and 1850 were later rearranged, condensed and edited by Fraser, his version was published in 1892 (this edition is usually attributed to Threlkeld). It includes a new orthography (writing system) designed by Fraser, who named language 'Awabakal' S66 which has since been adopted by the community (1892:preface).

Arposio (2008:10) describes Awabakal S66 as a dialect within a larger language group including Gadhang E67 to the north and extending southwards from Newcastle down the coast to the northern shores of Botany Bay, reflecting Fraser's (1892) 'Kuringgai' group.

Lissarrague describes the Hunter River - Lake Macquarie language (S99) spoken by people now known as Awabakal S66, Kuringgai S62, Wonnarua S63 and possibly Geawegal E1 (2006:8).

In Wafer and Lissarrague, Awabakal S66 is treated as a dialect name of the Hunter River - Lake Macquarie language, the other dialects being Wanarruwa S63 and Karikal S62, the latter is also known as Kurringgai, which Wafer and Lissarrague speculate is another invention of Fraser (2008:159-160). Their paper in 2010 disambiguates the different uses of this term.

Wafer and Lissarrague (2008) also address the confusion over the relationship between the Hunter River - Lake Macquarie language (S99) (i.e. Wanarruwa 63, Karikal ~ Kuringgai S62, Kayawaykal E1) and the 'Lower North Coast language' (i.e. Gathang E67, Birrpay E3, Warrimay E2 and Guringay E95), indicating these are two distinct languages.