SANAA, Yemen — The conventional wisdom goes something like this: As more and more Yemenis take to the streets, the growing civil unrest will force the already fractured state into chaos, providing a safe haven for Al Qaeda, which will use the country as a launching pad for attacks against the West.

But as the demonstrators march on, and the protests spread to other parts of the country, something very different appears to be happening. Yemen’s disparate groups — rival tribes, the Houthi rebels in the north and the separatist movement in the south — are instead setting aside old grievances and coalescing around a single cause: the ouster of Yemeni President Ali Abdullah Saleh.

Never in the recent history of this deeply fractured country, in fact, has it appeared so unified. And, analysts say, a unified country, coupled with a legitimate government, would likely be Al Qaeda’s ultimate undoing here.

That’s not the view of the U.S. and British governments, which have both warned of a resurgent Al Qaeda if the unrest in Yemen continues.

"If that government collapses, or is replaced by one who is dramatically more weak, then I think we'd face some additional challenges out of Yemen, there's no question about it. It's a real problem," said U.S. Secretary of Defense Robert Gates, referring to Al Qaeda, during a press conference last month.

Yemen became a single country in 1991 when the former Yemen Arab Republic and the People’s Democratic Republic of Yemen joined. But the two halves never truly became a whole and often fought each other for power. Ever since civil war broke out in 1994, the Yemeni government has struggled to rein in the rebellious south.

But now, with protests against Saleh sweeping the nation, many members of the so-called Southern Movement are leaving the organization to add their voices to those in the north who are demanding regime change, facing what has for them become the familiar reality of tear gas and riot police.

“We don’t need to secede from the north once Saleh is gone. Our problems in the south stem from a corrupt government,” said Nuha Jamal, 25, a youth activist in Aden, the former capital of South Yemen. “People are leaving the Southern Movement. We are all one in demanding that Saleh leave power. All of Yemen is united in this cause.”

A north-south conflict, however, is only one of the many divisions Yemen faces.

Saleh has also been locked into a series of conflicts with the Houthi rebels, who belong to a Shia sect based in Saada, Yemen’s northern province that borders Saudi Arabia.

From 2004 until 2009, the Yemeni military fought six wars against the Houthis. The government claimed that the Houthi rebellion wanted to reinstate religious rule in North Yemen, while the Houthis said they were politically marginalized and opposed to Saleh’s close cooperation with the United States.

The Houthi wars ravaged a sizeable portion of the northern part of the country, creating one of the world’s largest refugee populations. As the wars continued, the already meager health care infrastructure was devastated, worsening the humanitarian crisis.

Many Houthi rebels, however, have now harnessed their animosity for the government, laid down their weapons and joined the thousands of protesters camped out in Change Square in Sanaa, Yemen’s capital. One Houthi leader, Ali Al-Emad, now lives under the protection of the 1st Armored Division, the same soldiers that besieged Saada for more than five years but defected to the opposition last month.

“Our vision is clear and we share this vision with all of Yemen. We call for a civil state and equal citizenship for all Yemenis. We demand true democracy,” he said.

The Houthis in Change Square said they felt that once they are included in the political process, there would be no need for war.

“We tried to create our own sovereign state in Saada,” Al-Emad said. “But now we are calling for unity and equal rights for all Yemenis.”

Al-Emad said he welcomed the defection of Yemen’s top military commander, Ali Muhsin Al-Ahmar, despite the fact that he was the commander of the government’s military forces that long fought the Houthi rebels.

“I met Ali Muhsin and I welcomed him. We are grateful for his protection,” Al-Emad said.

Yemen’s civil strife in recent years is set against a rural backdrop that dominates large swathes of the country, where government control is almost nonexistent. North Yemen’s tribes, for instance, have always wielded more power than the country’s government, forcing the country’s political leadership to curry favor with influential tribes.

As tribal law trumps government control in a large portion of rural Yemen, many rival tribes often clash over territorial claims or become locked into lengthy revenge battles.

But now, even rival tribes are sharing tents in Change Square. Two such tribes from the troublesome regions of Abeeda and Morad in Marib province have set aside their old enmity and joined each other, and the protest movement, in the capital.

“When tribes fight over land or take revenge for murdered relatives, Saleh smiles. This unrest simply enables his corruption to continue,” said Nasser Al-Qadhi, a sheikh from the Morad tribe in Marib.

“We’ve learned to forgive each other so we can join together to drive out this devil and take our country back from the hands of corruption. Once our new Yemen begins, we will turn our weapons over to a government that we trust to protect us,” the sheikh added.

The periodic unrest between rebels, separatists and rival tribes — and a lack of government control in rural regions — is what many think enabled Al Qaeda in the Arabian Peninsula to operate so freely in the provinces of Shabwa, Abyan, Lahj and Marib.

Yemenis, however, said they felt that Al Qaeda is a by-product of government corruption. Ahmed Al-Zurqa, a political analyst and expert on Al Qaeda, agreed.

“Al Qaeda will not threaten Yemen any longer,” he said. “The tribes have now joined the pro-democracy movement, leaving [Al Qaeda] without protectors or a refuge. Once the regime falls, [Al Qaeda] will disappear.”