For several centuries, the O'Donnells ruled Tír Chonaill (Tyrconnell), a túath or Gaelic kingdom in west Ulster that covered almost all of modern County Donegal.

The O'Donnell's royal or chiefly power was finally ended in what was then the newly created County Donegal in September 1607, following the Flight of the Earls from Portnamurray, near Rathmullan.

Although detachments of the Royal Irish Army were stationed there, the Dublin authorities were unable to establish control over Tír Chonaill and Inishowen until after the Battle of Kinsale in 1602.

During the Irish Civil War (1922–1923), Donegal played a strategic role due to its proximity to Northern Ireland, where anti-Treaty forces often sought refuge and resupplied.

The county's rugged landscape, including areas like Dunlewey,[12] provided ideal terrain for guerrilla operations and hiding arms caches.

Local communities were divided in their loyalties, with some supporting anti-Treaty forces by offering shelter and supplies, while Free state forces carried out raids to suppress resistance[13] The Ballymanus mine disaster occurred on 10 May 1943 on a beach at Ballymanus, County Donegal, when local villagers attempted to bring ashore an unexploded marine mine.

In May 1991, the prominent Sinn Féin politician Councillor Eddie Fullerton was assassinated by the Provisional IRA's opponent, the Ulster Defence Association (UDA), at his home in Buncrana.

This geographic isolation from the rest of the Republic has led to Donegal people maintaining a distinct cultural identity[17] and has been used to market the county with the slogan "Up here it's different".

[21] While baronies continue to be officially defined units, they ceased to have any administrative function following the Local Government Act 1898, and any changes to county boundaries after the mid-19th century are not reflected in their extent.

[27] The county was also ranked the 4th best region in the world by Lonely Planet's Best in Travel series for 2024, which called Donegal "purely wild with a big heart".

Much of the county's forests are commercial timber plantations which were initially established in the 1930s as a way to create rural employment in areas with poor agricultural land and high rates of emigration.

The Wild Ireland wildlife park near Burnfoot showcases some of Donegal's historic animal species that were hunted to extinction, including brown bears, lynxes and gray wolves.

Due to the topography of western Donegal, it receives orographic rainfall, where the air is forced to rise on contact with its mountainous coastline and subsequently cools and condenses, forming clouds.

Irish monthly record wind speeds for March, June, July, September, November and December have all been set at Malin Head.

[47] The oldest rocks on mainland Donegal are a quartzo-feldspathic paragneiss found around Lough Derg, which have been dated to 1.713 billion years ago.

According to the 2022 Census, the number of people (aged three and over) who stated that they could speak Irish in Donegal was 59,130 (35.4% of the county's total population) compared with 56,738 in 2016.

Donegal voters have a reputation nationally for being "conservative and contrarian", and have often voted against amendments to the Irish constitution which received broad support in the rest of Ireland.

The trend first emerged in 1958, when voters in Donegal overwhelmingly voted to alter the electoral system from proportional representation to first-past-the-post in a referendum which was defeated nationally.

The 23rd Amendment permitting the State to join the International Criminal Court in 2001 received the lowest support in Donegal, with just 55.8% of voters backing the proposal, compared with 64.2% nationally.

[71] In October 2018, 48.5% of voters in Donegal voted against repealing the offence of publishing or uttering blasphemous matter, the highest of any county and significantly above the national total of 35.15%.

Such people include Daniel O'Donnell, Phil Coulter, Shay Given, Packie Bonner, Pat Crerand, Seamus Coleman, the Brennan family and Jim McGuinness.

By the late 1950s, major work was required to upgrade the track, and the Irish Government was unwilling to supply the necessary funds, so 'the Wee Donegal', as it was affectionally known, was closed in 1960.

Donegal music has also influenced people not originally from the county including folk and pop singers Paul Brady and Phil Coulter.

Other acts to come out of Donegal include folk-rock band Goats Don't Shave, Eurovision contestant Mickey Joe Harte and indie rock group The Revs.

The MacGill Summer School in Glenties is named in his honour and attracts national interest as a forum for the analysis of current affairs.

In modern Irish, Donegal has produced a number of (sometimes controversial), authors such as the brothers Séamus Ó Grianna and Seosamh Mac Grianna from The Rosses and the contemporary (and controversial) Irish-language poet Cathal Ó Searcaigh from Gortahork in Cloughaneely, and where he is known to locals as Gúrú na gCnoc ('Guru of the Hills').

David Steele, from Upper Creevaugh, was a prominent Reformed Presbyterian, or Covenanter, a minister who emigrated to the United States in 1824.

These include Ulster Qualifying League Two side Letterkenny RFC, whose ground is named after Dave Gallaher, the captain of the 1905 New Zealand All Blacks touring team, who have since become known as The Originals.

Other notable athletes from Donegal include Paul Dolan, Caitriona Jennings and Brendan Boyce each of whom has represented Ireland at the international level.

Donegal's rugged landscape and coastline lends itself to active sports like climbing, mountain biking, hillwalking, surfing and kite-flying.