Here is some background about the region bordering Iran and Turkey.

- Mountainous north -

Situated in the rugged mountainous north of Iraq, the region is home to about five million people.

They are mainly Kurds, who are mostly Sunni Muslims, and a Turkmen minority.

Kurdish and Arabic are the official languages, and the capital is Arbil.

Of Indo-European origin, Kurds also live in Iran, Turkey and Syria.

- Long persecuted -

The struggle for an independent Kurdish state started during Britain's mandate in Iraq and was relaunched in 1961 by the Kurdistan Democratic Party (KDP) of Mustafa Barzani.

It erupted into an Iraqi-Kurd war that finished in 1970 with a peace accord that granted Kurds autonomy.

But this failed to materialise and a new conflict started in 1974, the Kurds quickly collapsing.

The following year, the KDP split with the creation of the revolutionary Patriotic Union of Kurdistan (PUK).

In 1987-1988, as the Iran-Iraq war neared its end, the regime of Saddam Hussein launched violent operations against the Kurds.

The Anfal campaign saw nearly 180,000 killed and more than 3,000 villages destroyed.

The regime's policy of "Arabisation" forced thousands to leave their homes, replaced by Arabs.

Baghdad used chemical weapons against the village of Halabja, killing 5,000 people.

- Autonomy -

Iraqi Kurdistan gained de facto autonomy after the 1991 Gulf War, when Western powers intervened to protect Kurds against an onslaught by Saddam's forces that led hundreds of thousands to flee to neighbouring countries.

In 1992 the Iraqi Kurds elected their first parliament and set up a government.

Clashes erupted in 1994 between the PUK and the KDP parties over the distribution of the region's resources, leaving 3,000 dead over four years.

In 2003 Kurds joined up with US troops to help overthrow Saddam. He was executed three years later.

Iraqi Kurdistan became formally autonomous as a federal republic in 2005, with Mustafa Barzani's son, Massud, elected president.

- US allies against IS -

In 2014 Kurdish forces took control of the oil-rich province of Kirkuk, profiting from the chaos created by the advance of the Islamic State (IS) group.

They became an important ally of the US-led coalition against the jihadists in zones bordering Kurdistan.

- Failed independence referendum -

On September 25, 2017 Iraqi Kurdistan voted for independence at a referendum initiated by Massud Barzani, despite warnings from Baghdad and the international community.

The referendum covered disputed border areas beyond the autonomous region, such as Kirkuk, and led Iraqi government forces to act to retake the oil-rich province.

Barzani stepped down as president. Since then Iraqi Kurdistan has been run by his nephew, Nechervan Barzani.

- Economically strapped -

Iraqi Kurdistan went through an economic boom after the 2003 US-led invasion of Iraq, as the rest of the country sank into violence.

However the emergence of IS in 2014 hit investments hard.

In the wake of last year's failed referendum, the loss of disputed territory, notably Kirkuk, deprived the region of essential oil revenues.

The central government withheld civil servant salaries, fuel prices rose and there were power cuts, feeding popular anger that erupted into days of protests in December.

Baghdad also imposed a blockade for nearly six months on two of the region's airports that was lifted in March 2018.