The district was originally inhabited by the Ngiyambaa Aborigines. Thomas Mitchell explored the Bogan River in 1835, camping on the future townsite. He recorded the local Aboriginal word 'nyingan', said to mean 'long pond of water', though other meanings have been put forward. Squatters had settled in Mitchell's wake before he had even begun the return journey.
The acting botanist with the expedition was Richard Cunningham, the younger brother of noted explorer Allan Cunningham. He was killed by Aborigines 84 km south-east of Nyngan when he got lost after straying from the main party (a cairn marks the spot, near the locality of Tabratong). Apparently Cunningham approached the Aborigines gesticulating that he was hungry. They fed him and he made camp with them but he aroused suspicions in the course of the night when he arose several times so they clubbed him to death while he slept. A cairn has been erected to mark the spot. The police investigated and arrested three men who readily confessed. Two later escaped and a third was taken to Sydney, his fate unknown.
This was not an isolated incident. Relationships with Aborigines on the lower Bogan River were characterised by conflict and, as a result, the government cancelled all pastoral licenses beyond the Derribong run in 1845.
A massacre occurred in the area in 1841. During a prolonged drought nine stockmen employed by William Lee set off from a station 16 km north of Peak Hill in search of water with 1200 cattle in tow. They came across a large waterhole, to the north of present-day Nyngan, where a large number of Aborigines were camped. The whites informed the Aborigines that only those who wished to work could stay and the rest must leave. Not surprisingly, this caused considerable ill-feeling. When one Aborigine shook his fist at the stockmen he was strung up by the wrists and whipped. One of the white men was concerned at the signs of growing resentment and tried to convince the others to leave but, failing in his endeavours, he departed on his own. He looked back later in the day and noted birds of prey hovering over the distant site. He returned and found three badly mutilated bodies and two survivors with severe wounds.
When the deaths were reported a police troop was sent to inflict punishment. It is said three were killed and three arrested but it is believed that hundreds more Aborigines were subsequently killed. Certainly when Thomas Mitchell revisited the area in 1845 he was surprised by the absence of Aborigines when he had estimated a thousand to live along the river during his 1835 expedition. When word of the massacres reached Governor Gipps he cancelled William Lee's squatting license.
The small town of Canonba was the first local settlement of any duration. It was established to the west of the Bogan and 28 km north-west of today's Nyngan. Cobb & Co made it a coach stop on the route north-west to Bourke and to the properties of the far west. Bushranger Charles Rutherford was shot by the owner of the Canonba Inn in 1867 while bailing up the establishment.
Nyngan was gazetted as a reserve for water in 1865 but a townsite was not reserved until 1880. It was surveyed in 1882 when the Dubbo-Bourke railway was under construction. The track arrived in Nyngan the following year, signalling the end of Canonba's existence. Symbolically enough, a number of houses from the older settlement were dismantled and re-erected at Nyngan in 1883.
By this time the initial emphasis on cattle had been balanced by the grazing of merino sheep for their wool. Wheat-growing also began in the 1880s although unreliable rainfall has always been a problem, as the Bogan only flows after rain. The town received a secure water supply in 1942 when water was relayed along a 62-km canal from the Macquarie River.
Nyngan became a municipality in 1891. A meatworks developed on the outskirts of town in the 1890s for the boiling down of sheep and an experimental farm was established in 1910 to further wheat cultivation.
Nyngan, little known in the east, entered the national psyche in 1990 when it was deluged with the worst floods of the century. The townspeople laid 260 000 sandbags on top of the established levee but the waters inundated the entire town, causing $50 million worth of damage and necessitating the airlift by helicopter of 2000 citizens, virtually the entire population. A national relief fund was established to help the town recover.
Today Nyngan's role as a rail centre has terminated with the cancellation of the service to Bourke and it is now a service centre to the surrounding district. The Agricultural Show is held in May.