It’s not clear when the slogan emerged, but scholars say it started gaining traction in the 1960s among Palestinian activists and intellectuals who were made refugees by the 1948 war.
During that conflict, an estimated 700,000 Palestinians either fled or were expelled from their homes by Israeli forces, after which the state of Israel was established. Many of them settled in the West Bank, which was later annexed by Jordan, and in Gaza, which was administered by Egypt. (Israel captured both territories in the 1967 war with neighboring Arab states).
Palestinian refugees began developing the idea of a “free Palestine” — a “secular, democratic, free” state, from the Jordan River to the Mediterranean Sea, said Maha Nassar, an associate professor of Middle East history and Islamic Studies at the University of Arizona.
Later, the phrase was taken up by supporters of the Palestine Liberation Organization, or PLO, the coalition founded in 1964 that remains the official representative of the Palestinian people at the United Nations. In the rounds of conflicts and uprisings in the decades that followed, it became popular among different Palestinian factions.
More recently, supporters of Hamas, the militant group that controls Gaza, have adopted the slogan. The group’s charter, in which the phrase does not appear, calls for a movement that “hits deep into the earth and spreads to hug the sky.”
“Palestine is ours from the river to the sea and from the south to the north,” Khaled Mashaal, the group’s former leader, said in a 2012 speech in Gaza celebrating the 25th anniversary of the founding of Hamas, the Associated Press reported.