From wikipedia https://en.wikipedia.org/wiki/Palestinian_nationalism#From_the_river_to_the_sea
From the river to the sea
"Palestine from the river to the sea" was claimed as Palestine by the PLO[65] from its establishment in 1964 until the signing of the Oslo Accords.[78] The PLO claim was originally set on areas, controlled by the State of Israel prior to 1967 War, meaning the combined Coastal Plain, Galilee, Yizrael Valley, Arava Valley and Negev Desert, but excluding West Bank (controlled then by Jordan) and Gaza Strip (occupied between 1959 and 1967 by Egypt). In a slightly different fashion "Palestine from the river to the sea" is still claimed by Hamas,[79] referring to all areas of former Mandatory Palestine.
From the River to the Sea (Arabic: min al-nahr ila al-bahr ) is, and forms part of, a popular political slogan used by Palestinian nationalists. It contains the notion that the land which lies between the River Jordan and the Mediterranean Sea be entirely placed under Arab rule at the cost of the State of Israel, excluding the contested Golan Heights, conquered from Syria in 1967 and unilaterally annexed in 1981.[80] It has been used frequently by Arab leaders[81][82] and is often chanted at anti-Israel demonstrations.[83]
The slogan is versatile with numerous variations including "From the river to the sea, Palestine will be free,"[84] "Palestine is ours from the river to the sea," "Palestine is Islamic from the river to the sea,"[85] Islamic scholars also claim the Mahdi will also declare the slogan in the following format: "Jerusalem is Arab Muslim, and Palestine all of it, from the river to the sea is Arab Muslim."[86]