Palestinians gathered on Sunday in the occupied West Bank city of Ramallah to mark the anniversary of the displacement of hundreds of thousands of refugees from what is now Israel during the 1948 war surrounding its creation.
Nakba Day, Arabic for "catastrophe," comes amid a wave of Israeli-Palestinian violence that has been fueled by tensions at a key Jerusalem holy site.
At least 18 people have been killed in Palestinian attacks in recent weeks, as well as more than 30 Palestinians, most of them involved in attacks or clashes with Israeli forces.
On Friday, during a funeral for slain Al Jazeera journalist Shireen Abu Akleh, Israeli riot police pushed and beat pallbearers, causing them to briefly drop the casket.
The scenes of violence likely added to the sense of grief and outrage across the Arab world that has followed the death of Abu Akleh, who witnesses say was killed by Israeli troops Wednesday during a raid in the occupied West Bank.
It also illustrated the deep sensitivities over east Jerusalem - which is claimed by both Israel and the Palestinians and has sparked repeated rounds of violence.
Some 700,000 Palestinians fled or were driven from their homes during the 1948 war.
Today, they and their descendants number around 5.7 million and mostly reside in the West Bank, Gaza, Jordan, Lebanon and Syria.
The Palestinians say they are entitled to a right of return, something Israel rejects because if it were fully implemented, then Palestinians would become a majority in the country.
The fate of the refugees has been one of the most divisive issues in the peace process, which ground to a halt more than a decade ago.