AROUND four millennia ago, squeezed out of their homelands by three empires, a collection of tribes arrived in what is now the frontier region of Turkey, Iraq and Iran. Largely nomadic, they nevertheless decided to make their home among the mountains and plateaus, herding sheep, cattle and goats. By the beginning of the 7th century, some 2,400 years later, they had been given a name: Kurds.

Now the Kurds are at the heart of the argument for toppling Saddam. Along with his possession, or development, of weapons of mass destruction, it is the Iraqi dictator's treatment of his own people which forms much of the case against him.

And it is a powerful case. The Iran-Iraq war of the 1980s saw Iraq's Kurdish population support the Iranians. Following a truce between the two sides in 1988, Saddam wreaked his revenge. In two years, some 180,000 Kurdish men were butchered in a campaign known as Anfal. Thousands of villages were razed. Entire communities were transported to the south-west of Iraq and buried alive in mass graves in the desert.

The most notorious atrocity was the chemical weapons attack on the town of Halabja on March 16, 1988, when 5,000 Kurds were killed.

But the Kurds' misfortunes did not start with Saddam, and their history over the 20th century is one of betrayal, division and repression.

For a taste of how this history has imprinted itself on the Kurdish psyche, look no further than the lyrics of the Kurdish national anthem:

Nobody should say the Kurds are dead because the Kurds are alive,

Our banner shall never be lowered,

Our homeland is our faith and religion,

We are the heroes of revolution and the colour red,

Just look how bloodstained our history is,

The Kurdish people are gallantly standing to attention,

Ready to decorate their living crown with blood,

The Kurdish youth is ever present and ready to sacrifice their lives.

At the break-up of the Ottoman Empire following the First World War, the Kurds pressed for their own state, using their bitter struggle against Ottoman rule and the Allies' failure to protect them as powerful bargaining tools. On August 10, 1920, the Allies signed the Treaty of Sevres, providing for the creation of an autonomous Kurdish state. But the military revival of Turkey under Kemal Attaturk meant that when Sevres was superseded by the Treaty of Lausanne in 1923, there was no mention of a Kurdish nation. From that time on, international support for a Kurdish state disappeared.

The area occupied by the Kurds has been known as Kurdistan since the beginning of the 13th century, covering 74,000 sq miles over eastern Turkey, north-eastern Iraq, north-western Iran and parts of north-eastern Syria and Armenia.

Ethnically close to the Iranians, the majority of Kurds are Sunni Muslims, although their primary loyalties are to their families and their tribes. Nor are they united by language: they lack a common tongue and cannot always communicate with other Kurds. The majority speak a language originating in north-western Iran but split into two dialects, both with major local variations, and with several sub-dialects.

Following the collapse of the dream to create an independent Kurdish state through diplomacy, there have been several attempts to win greater freedom through force. Revolts by the Kurds of Turkey in 1925 and 1930 were quashed and many thousands were killed through bombing, shelling and poison gas in 1937-8.

From the mid-1980s, the Turkish government has been locked in a bitter war with the Revolutionary Kurdish Labour Party (PKK), the only Kurdish movement to advocate complete independence. Terrorist attacks by the PKK are met with brutal repression - a government attack in 1992 killed more than 20,000 Kurds and left another two million refugees. Altogether, an estimated 30,000 people are estimated to have died in the conflict.

In Iran, the Kurds have achieved a measure of cultural independence but have largely been excluded from wielding political power and attempts at self-government have been suppressed. Around 130,000 Kurds fled to Iran during the war between Iran and Iraq in 1974, but in 1993 there were a number of outbreaks of armed struggle in Iranian Kurdistan.

Attempts by the Kurds of Iraq to achieve a degree of autonomy have been ruthlessly crushed by the ruling Ba'ath party, even before the advent of Saddam. Revolts in 1919, 1923 and 1932 were swiftly quelled. A 1970 agreement gave them some degree of self-government, but this later fell through.

But following Saddam's brutality in the late 1980s, there was real progress at the end of the Gulf War. A Kurdish uprising was crushed by Iraqi troops, with half a million Kurds fleeing to the Turkish border and one million to Iran, but subsequent UN intervention saw the establishment of an international guaranteed enclave in northern Iraq, supported by Western sanctions and patrolled by the US and British air forces.

Around two thirds of Iraqi Kurdistan is now under Kurdish control, covering 50,000 sq kilometres and populated by 3.5 million people, around 500,000 of them refugees. But even with this the Kurdish aspirations have not been fulfilled. The enclave does not include Kirkuk, the capital of Kurdistan but of vital strategic importance to Saddam as the centre of Iraq's northern oil fields.

And not all the Kurdish problems have been external. In 1994, open warfare erupted between the two major Kurdish guerrilla groups, the Patriotic Union of Kurdistan (PUK) and the Kurdish Democratic Party (KDP), which had previously shared power.

A series of clashes eventually saw the KDP control the north-western part of the enclave, with the PUK exercising mastery over the south-eastern corner. This internecine struggle saw Saddam support the KDP, with some 40,000 troops, and suspected Iranian assistance for the PUK, until both sides agreed to end hostilities in 1999.

For the Iraqi Kurds, they have already come a long way towards their goal of autonomy, albeit underwritten by Western air superiority and with the Saddam pursuing a policy of 'Arabising' Kirkuk, displacing Kurds with Arabs. But this position would be much stronger in a post-Saddam Iraq, giving them hope of freedom from the threat of repression once the West turns its back.

But the war of liberation could also spell danger for the Iraqi Kurds. An invasion of Iraq could provide Turkey with an opportunity to try and gain influence over northern Iraq, and with the Turkish antipathy towards a separate Kurdish state, this could imperil the Kurdish enclave. For a people who have been faced with enormous and brutal hurdles in their 4,000-year evolution towards nationhood, it would be ironic if it were to be torn from their grasp as a result of a war of liberation.