The Arab enemies of Israel have told themselves for decades that Zionists wish to conquer the central Middle East, more specifically from the Nile River in Egypt to the Euphrates River in Iraq. I reviewed this subject in depth in 1994 in "Imperial Israel: The Nile-to-Euphrates Calumny" and note here when this conspiracy theory notably reappears.
1997-2007: Itamar Marcus and Barbara Crook of Palestinian Media Watch (PMW) collect nearly two dozen instances of this theme in the Palestinian media over the past decade at "From the Nile to the Euphrates - PA continuous libel (1997-2007) about secret plan to conquer Arab nation." (June 12, 2007)
Mar. 23, 2014 update: PMW reports that Fatah spokesman Ahmad Assaf repeated the Nile-to-Euphrates libel twice in the same week, both times in Egypt.
May 27, 2020 update: PMW reports on an article by columnist Bassem Barhoum in the official Palestinian Authority daily, Al-Hayat Al-Jadida, on May 15, 2020: "The goal is to stop the expansion of the greedy Zionist cancer, at a time when the saying 'From the Nile [River] to the Euphrates [River]' is still arousing the desires of leaders in Israel."
June 29, 2020 update: Mahmoud Khalifa, a retired general and the military advisor to the Secretary-General of the Arab League, ascribed to the Protocols of the Elders of Zion a Jewish ambition to rule from the Nile to the Euphrates and gather in world Jewry there preliminary to further expansion.
Aug. 30, 2020 update: A Palestinian scholar of Islam, Omar Fora, stated that "Israel wants to establish 'Greater Israel.' By Allah, the day will come when Israel demands lands in Medina" and elsewhere in what is today Saudi Arabia. He also offered a novel theory for why Israel's embassy in Egypt is in Giza: "it established its embassy west of the Nile, because it considers the land west of the Nile to be outside its territory."
Apr. 25, 2022 update: Yemen's deputy minister of higher education, Ali Yahya Sharaf al-Din:
The people and the students of the Arab world should know the meaning of the Israeli flag. It consists of two entwined triangles, representing religion and state, and two blue stripes, one at the bottom and one at the top, representing the efforts of Israel, that religious state, to take large parts of our Arab countries, from the Euphrates to the Nile. This used to be in our school curricula in the past, but it was removed from the school curricula in all the Arab and Islamic countries under British and American order, as we all know, to make the people unaware of this.