The new leadership installed after the overthrow of Egyptian president Hosni Mubarak "kept an equal distance from both the parties," he added.
The Egyptian revolt removed intelligence chief Omar Suleiman, whom Hamas had accused of favouring Fatah, while also depriving Palestinian president Mahmud Abbas of a key supporter in Mubarak.
Azzam al-Ahmed, who headed Fatah's delegation in Cairo, said the "Arab spring placed pressure" on both factions to heal their rift, which had left the Palestinians with rival governments in Gaza and the West Bank.
"The people began to feel and demand their freedom," he said. "There was real pressure by all the factions and the Palestinian youth."
On March 15, tens of thousands of Palestinians took to the streets of the West Bank and Gaza to demand the two sides work towards a unity government, and many welcomed Wednesday's announcement of a deal.
But Ahmed also credited efforts by Abbas, who sat down with senior Hamas officials in the West Bank city of Ramallah on March 26 in a bid to break the deadlock.
"Starting from Abu Mazen's initiative, communications were ongoing," he said, using Abbas's nom-de-guerre. "It was direct talks that proved effective.
Commentator Hani al-Masri said the political changes in Egypt and the broader Middle East were a key driver for the reconciliation "in the sense that there are fewer parties able to block the deal because they are concerned with their own internal situation."
Officials said the continuing stalemate in talks with Israel also helped push the two parties back into talks.
Mahmud Zahar, a senior Hamas official and part of its delegation to Cairo, said the deal was the result of "a change in the (regional) political environment and the failure in negotiations."
Mussa Abu Marzuk, a top member of Hamas's exiled leadership in Damascus, also credited the efforts of Palestinian MP Mustafa al-Barghuti, who heads the political party called the Palestinian National Initiative.
Speaking to AFP on Thursday, Barghuti welcomed the deal as "a victory for the Palestinian people and its national unity," but analysts warned it was only the first step in a long process of reconciliation fraught with pitfalls.
Masri said "the signing is a very important first step but implementation is the most important thing and the most dangerous."
Georges Giacaman, a political analyst and professor at Bir Zeit University, echoed Masri's caution.
"We must not forget that, so far, the deal is just on paper and all the issues and the elections are on hold for a year," he told AFP.
Among the issues likely to be put on the back burner is the divided Palestinian security establishment, with both sides currently running their own forces in their respective areas of control.
The deal calls for the establishment of a joint high security council to begin work straight away on restructuring and professionalising the security forces, but no changes will be made before elections, officials told AFP.