WASHINGTON -- Ever since Iraq became a nation in 1921, its Kurdish population has been engaged in an almost constant rebellion for some degree of autonomy against the government in Baghdad.
In recent weeks, the Kurds have made extraordinary military gains against the government of President Saddam Hussein, seizing most of the territory that makes up Iraqi Kurdistan, including the crucial oil center of Kirkuk.
Jalal Talabani, leader of one of two principal Iraqi Kurdish groups, returned triumphantly Tuesday to Zakho, a Kurdish city in northern Iraq, after three years in exile.
Mr. Talabani has hoped to use the recent string of Kurdish military victories to call a meeting of Kurdish leaders, including Massoud Barzani, the other principal opposition figure, to discuss creating a provisional government.
But much of the reason the Kurds have done so well is that the Iraqi army has been busy suppressing a separate rebellion in more than a dozen Iraqi Shiite cities in the south.
Now that the army has largely brought the south under control, according to reports, it is expected to move north and focus on the Kurdish revolt, now by far the most serious it has been in two decades. Some administration officials predict that ultimately the army will prevail, as it has consistently done in the past.
About 20 percent of Iraq's 18 million people are Kurds, an ancient Indo-European, largely Sunni Muslim people with their own language, culture and traditions. They form the fourth-largest ethnic and linguistic group in the region after Arabs, Turks and Persians. Now numbering more than 20 million, they live in a wide arc that stretches from Iran in the east to Iraq and Turkey, with much smaller communities in Syria and the Soviet Union.
The current turmoil had its genesis in the 1920 Treaty of Sevres, which carved Iraq, Syria and Kuwait from the Ottoman Empire after World War I, promised the Kurds "a scheme of local autonomy" and recognized their right to form an independent Kurdish state in the eastern portion of what later became Turkey.
But with the coming to power of Kemal Ataturk and his fierce nationalism and policy of ethnic assimilation in Turkey three years later, the treaty was never implemented.
A subsequent treaty signed in Lausanne, Switzerland, in 1923 omitted any reference to the rights of the Kurds.
No Kurdish revolt has ever brought down an Iraqi government, although an inability to crush rebellions contributed to the overthrow of several governments before the Arab Baath Socialist Party came to power in 1968.
The Kurdish opposition is led by two main groups that control considerable guerrilla forces, the Kurdish Democratic Party, led by Mr. Barzani, and the Patriotic Union of Kurdistan, led by Mr. Talabani.
Mr. Barzani, who is in his 30s, is the son of the late Mustafa Barzani, a legendary Kurdish leader who with the help of Soviet ** troops in 1946 set up the short-lived Kurdish Republic of Mahabad in northern Iran.
The younger Mr. Barzani spends most of his time in his mountain headquarters near the point where Iraq, Turkey and Iran meet, and his troops are more numerous and better-trained and disciplined than are those of Mr. Talabani.
Mr. Talabani, a former journalist and lawyer in his late 50s, hardly fits the image of a leader of guerrilla warriors known as "pesh mergas" or "those who walk before death." In recent years he has divided his time between Damascus, Syria, and London, acting as a sort of roving emissary and political operative.
The split between the groups is less ideological than it is personal and geographic, and in recent years the two men have made an effort to bury their differences and forge a common front. In 1988 they joined with other smaller Kurdish parties, including Socialists, Marxists and Communists, to form the Iraqi Kurdistan Front.
Over the years, the Kurdish groups in Iraq have scaled back their demands, acknowledging that self-determination is a pipe dream and calling instead for autonomy in their internal affairs.
"You have to judge political objectives according to realistic expectations," Mr. Talabani said in an interview in November. "We don't want to be like the Palestinians and ask for the impossible. If there were a democratic government in Iraq, we would be happy to be Iraqis."
Under no circumstances will the Kurdish opposition collaborate with the Hussein government in Baghdad. In 1970 the Kurds signed an agreement that gave them an autonomous region and allowed the Kurdish language to be taught in schools. But the agreement collapsed and the Kurds, with aid from Iran, Israel and the CIA, rebelled again in 1974.
The rebellion became so serious that in March 1975, Mr. Hussein abruptly signed an accord with the shah of Iran to end Tehran's meddling. The Kurdish rebellion collapsed, and the elder Mr. Barzani, who had led the revolt, went into exile in the United States. He died in 1979.
During the Iran-Iraq war, the Baghdad government moved ruthlessly against Kurdish rebels. Mr. Hussein used chemical weapons against Kurdish civilians, razed villages and forced thousands of Kurds to relocate.