GAZA CITY, Gaza Strip (AP) — The Fatah party of Western-backed Palestinian President Mahmoud Abbas staged a massive rally Friday in the Gaza Strip, the first such gathering in the territory since the Islamist Hamas group took control there in 2007 and a reflection of the warming ties between the two rival factions.

Throngs camped out overnight in a downtown Gaza square to ensure themselves a spot for the anniversary commemoration of Fatah’s 1959 founding, and tens of thousands marched early Friday carrying Fatah banners.

Top party officials arrived in Gaza for the first time since they were ousted from Gaza by Hamas rivals in 2007, and a recorded speech by Abbas, who rules in the West Bank, was also screened to the crowd.

"There is no substitute for national unity," Abbas said in the televised address.

Hamas has gained new support among Palestinians following eight days of fighting with Israel in November, in which its militants lobbed rockets toward the heartland Israeli cities of Jerusalem and Tel Aviv for the first time. After the fighting, relations have thawed between Hamas and Fatah, and Hamas was allowed to hold its first West Bank rallies since the 2007 split in which Hamas seized Gaza and the secular-leaning Fatah was left in control of the West Bank.

Senior Fatah official Nabil Shaath said the party received a congratulatory message from Hamas Prime Minister Ismail Haniyeh, who expressed hope that the two factions could reconcile their differences and work together as joint representatives of the Palestinian people.

"This festival will be like a wedding celebration for Palestine, Jerusalem, the prisoners, the refugees and all the Palestinians," said Shaath.

Reconciliation between the two factions, however, is still far from coming to fruition. Hamas chief Khaled Mashaal, considered more pragmatic than Hamas’ Gaza-based hard-line leaders, forged a reconciliation agreement with Abbas in 2011.

But the Gaza-based leadership, unsupportive of the agreement, has held up implementing it. Also, Fatah enjoys Western support and it has been pressured not to forge a unity deal with the militant Hamas.

Fadwa Taleb, 46, who worked as a police officer during the previous rule of Fatah, gathered at the rally with her family. "We feel like birds freed from our cage today," Taleb said. "We are happy and feel powerful again."

A Gaza security official said a Fatah-linked former aide to the late Palestinian leader Yasser Arafat died of a heart attack in the square overnight, saying he was shocked by the large crowd that was allowed to gather.

In the West Bank, Palestinian President Abbas signed a presidential decree changing the name of the Palestinian Authority to the "State of Palestine," following the Palestinians’ upgraded status at the United Nations as a non-member observer state.

According to the decree, reported by the official Palestinian news agency Wafa Thursday night, all stamps, signs, and official letterhead will be changed to bear the new name.

It is the first concrete, albeit symbolic, step the Palestinians have taken following the November decision by the United Nations. Abbas has hesitated to take more dramatic steps, like filing war crimes indictments against Israel at the International Criminal Court, a tactic that only a recognized state can carry out.