The proposed Iraqi constitution that would enshrine a measure of independence for the country's ethnic Kurds is viewed with apprehension by three neighbors already struggling to accommodate the aspirations of their own Kurdish populations.

Syria, Turkey, Iran and Iraq each share a portion of the mountainous expanse of the Middle East long inhabited by ethnic Kurds, who are thought to number around 27 million. A minority in each country, the Kurds are united by language, vibrant customs and an abiding sense of grievance over being denied a country of their own. They were promised one as the victors began drawing lines on maps after World War I, but when the ink dried, Kurdistan had been divided among four other countries.

Then three Great Powers -- the United States, Britain and France -- returned to the region in 1991, to fight the Persian Gulf War. It ended with Kurds in Iraq's rugged north essentially left alone to rule themselves under the protection of U.S. and British air patrols. Twelve years later, their enclave served as a staging ground for the 2003 invasion.

On Saturday, voters across Iraq will decide on a constitution that would acknowledge Kurdish quasi-independence as the law of the land. The document offers legal sanction to an extensive autonomy that already has inspired hopes among Kurds looking on intently from the east, north and west.

In Syria, where Kurds account for about 9 percent of the population of 18 million, the north of the country has been tense since rioting broke out in several Kurdish cities in March 2004. The unrest, which left at least 30 dead after government troops opened fire, began at a soccer game where Kurds' chants of "George Bush!" were answered by Arabs' chants of "Long live Saddam Hussein!"

"The Kurds were clearly emboldened by what was happening in Iraq," said Joshua Landis, a University of Oklahoma historian who is in Syria as a Fulbright scholar. He noted that the soccer game occurred just after Washington endorsed Iraqi laws that gave Kurds veto power over a new constitution.

"In a sense, this just changed the whole environment among the Kurds, because it was seen as the U.S. endorsing Kurdish independence," Landis said.

In the aftermath of the unrest, Syrian security forces clamped down on travel by outsiders to Kurdish areas. But Damascus also began to invest there and even floated the possibility of restoring full citizenship to some 300,000 Kurds stripped of that status decades earlier.

Analysts said the gesture stalled amid fears that Kurds would form an alliance with other groups opposing the Baathist rule of President Bashar Assad. The intrigues grew with the murder last May of a prominent Kurdish sheik, Mashuq Khasnawi, who had openly solicited alliance with the Muslim Brotherhood, an Arab group with roots in political Islam that is banned in Syria.

A government spokeswoman said Syria had no official comment on Iraq's proposed constitution.

Iran faced mass demonstrations in several majority-Kurdish cities this summer, sparked by the death in police custody of a Kurdish activist whose body security agents dragged behind a truck in Mahabad, a center of Kurdish nationalism. Activists said that helicopter gunships opened fire on crowds in another city, a charge that Iran denied.

"What is going on in Iraq has a significant effect in Iran, especially in Kurdish Iran," said Morteza Esfandiari, a Washington representative of the Democratic Party of Iranian Kurdistan, which seeks independence. "The border is pretty loose."

Many of the perhaps 6 million Kurds in Iran complain of neglect by the country's Persian majority, a complaint shared by other ethnic minorities. Esfandiari said five groups, including ethnic Azeris and Baluchs from the desert southeast, have banded together in a Congress of Iranian Nationalities for Federalism.

Such expressions of diversity undercut the image of Iran as a monolith defined by Shiite Islam. But because the vast majority of Iraqis are Shiites, Iran's theocratic government generally favors the constitution that will empower them, said Hamid Reza Haji Babaei, an Iranian lawmaker quoted on a parliament Web site.

Iran's main concern about the Iraqi document involved "the integrity of the country in a new federalist form," Babaei said, citing Kurdish separatist activity in Iran's own past. As for "unrest in Kurdish towns and cities in Iran after the draft of Iraq's constitution was published," as Mahabad's Gov. Seyed Maroof Samadi described the unrest to the government press agency IRNA, the blame was on "adventurous individuals."

Turkey brings the most painful recent history to the issue of Kurdish independence. It fought a civil war against the separatist Kurdistan Workers' Party, known by the Kurdish initials PKK, in the country's vast southeast through the 1990s. Both the Turkish army and the PKK still have garrisons in northern Iraq, and the PKK resumed fighting inside Turkey last year. Five Turkish soldiers have been killed in clashes this week.

After complaining for two years that U.S. forces were not moving against the PKK's bases in Iraq, Turkish officials say they have found common ground with Washington, which has begun quietly targeting PKK infrastructure.

At the same time, Turkey has built new bridges to Syria and Iran based on their common interest in containing Kurdish ambitions. The rapprochement with Syria is especially striking. After decades of estrangement over border issues and Syrian support for the PKK, the countries exchanged state visits for the first time in decades.

"Our shared concern is to have a stable neighbor with stable borders in order not to have chaos in the region," said Ahmet Davutoglu, foreign policy adviser to Turkey's prime minister.

Relations are even more complex on the Kurdish side of the equation. Iraq's Kurdish parties have shifting histories of dependence on the governments of Syria and Iran from their days as exile groups aligned against Saddam Hussein. Now that Iraqi Kurds hold key positions in Baghdad, including the presidency, their duties include capturing wayward Kurdish guerrillas who cross over from Iran.

"We've had our pesh merga handed over to the Islamic Republic of Iran" by Iraqi Kurds, said Esfandiari, referring to Kurdish militiamen. "So it is very complex."