No longer in use as the name of a Sydney suburb, Liberty Plains refers to the land in the care of the Wangal people of the Eora/Dharawal language group. 
The first land grants
The earliest use of the name is found in the description of grants of land to Thomas Rose, Frederick Meredith, Thomas Webb and Edward Powell on 28 May 1793. They had arrived as passengers on the Bellona in January of the same year. With the help of families and servants, they cleared the land and grew wheat and corn. However, the fertility of the ground was exhausted within four to five years, so that their families were dependent on government rations. 
Some later histories suggest that the name emerged because these were the first free settlers to arrive in the colony who were given land grants.  However, there were other passengers given adjacent grants, with the description there being 'the District of Concord'.
Clearing the land was slow. Samuel Crane was killed in 1794 by a falling tree when felling timber on his 25 acres (10 hectares) at Concord. His farm was advertised for sale as having 'a comfortable hut, four acres planted to corn and half an acre to potatoes'. 
Again, Liberty Plains was used in 1797, referring to grants to Henry Waterhouse and John Shortland, and in 1800, to Isaac Archer on the Homebush Bay peninsula. Simeon Lord offered Captain Waterhouse's 25 acres (10 hectares) for sale in the Sydney Gazette of 6 January 1805. The interesting feature of the advertisement is 'NB All persons are prohibited from cutting spars or timber of any kind on the above grounds'. This would suggest that no-one was living there at that time. It is doubtful that these grants were occupied, as they were all purchased by John Blaxland in 1808, to be consolidated in his Newington Estate. 
These descriptions of land grants include the area between Concord and Duck River to the west, within what are now the suburbs of Lidcombe, Auburn, Newington and Homebush Bay. Licences to sell beer on Parramatta Road were granted to Thomas Bates in 1809 and Samuel Haslem in 1811.  Liberty Plains is mentioned as an assembly point for the 1807 muster, and as a place visited by Governor Macquarie in his first tour of the colony in 1810. 
Liberty Plains no longer
An analysis of the 1828 census suggests that there was a population of 137 in the area now included in the Auburn local government area. At the time, there were seven properties in use, owned or occupied by John Blaxland, D'Arcy Wentworth, P William Plomer, HG Douglas (managed by Patrick McGonnigle), James and William Haslem, Samuel Haslem, Ann Curtis and James Wright. 
On 13 June 1831, William Webber was convicted of highway robbery against Francis Watkins 'at Liberty'. In the trial before Mr Justice Stephen, doubts were raised by the defence as to whether the place of the offence was properly described in the indictment: 'His Honor did not think the objection valid'. 
The name Liberty Plains slowly passed out of common use, as it came to be adopted as a name for a parish in the systemisation of land descriptions in New South Wales.  The boundaries of the parish are Parramatta, Woodville and Liverpool roads and the boundary between Lidcombe and Flemington, and it is smaller than the area described when the name was in common use.
Haslem's Creek emerged as the new common name for the eastern half of Liberty Plains. The creek associated with the locality formed one boundary of the grant to William and James Haslem. Later name changes were to Rookwood in 1876 and Lidcombe in 1913. 
Council of the Municipality of Auburn, Liberty Plains: A History of Auburn, NSW, the council, Auburn NSW, 1993