Allow me to try my best and create a small summary of the events. There are a lot of sources, (and when I say a lot, I mean I literally cannot list them here, and half of them are not internet sources which I can link you to. You would have to go out and buy books, go to the library, or check the original maps yourself if you disbelieve it. But with a quick google search you will find there is a consensus that these land distribution numbers are correct and the maps accurately depict the Palestine Mandate and UN Partition Plans. Even die hard anti-Israel critics have not challenged them. They're just sourced from various British and UN documents.)
Here is the simplest map I can find, which just colors in the areas according to time/region.
The area of the original Palestine Mandate was 118,000 square kilometers. The entire Palestine Mandate was originally
In 1921, a partition plan was proposed that would give the Arab residents the 91,000 square kilometers to the east of the Jordan River for them to create a state of their own, and west of the Jordan River would be reserved for a Jewish state. The Zionists agreed to it. In 1922, the League of Nations Council (the precursor to the UN) approved the Churchill White Paper which included the proposal. Jews were not allowed to settle in Trans-Jordan, but the Arabs west of Jordan River were free to stay. By 1923, it was in effect.
It was named Trans-Jordan, meaning "Across Jordan", referring to the river. Eventually it was named Jordan, after said river.
Over the next years violence broke out against the Jews, which is another story. There was a second White Paper in 1939, but I'm not going to get into that. Eventually the British handed over the territory west of the Jordan River to the UN. The UN wanted to stop the violence, so they offered the Arabs more land and intended to make two states in 1947. One Jewish Palestinian state, and another Arab Palestinian state. This was the proposed arrangement.
The Jewish Palestinians accepted this proposal, but the Arab Palestinians rejected it and declared war. The 1948 War of Independence. They lost and during the war the hotly debated Naqba occurred.
A lot more interesting stuff happened afterwards and to this day, but this post is getting really long trying to explain the 4/5ths of Palestine Mandate statement.
Text of Mandate:
http://www.mtholyoke.edu/acad/intrel/britman.htmText of first Churchill White Paper:
http://avalon.law.yale.edu/20th_century/brwh1922.aspText of San Remo Convention:
http://wwi.lib.byu.edu/index.php/San_Remo_ConventionPalestine becoming Transjordan/Jordan :
http://www.archiveeditions.co.uk/titledetails.asp?tid=96 http://www.palestinefacts.org/pf_mandate_transjordan.phphttp://www.palestinefacts.org/pf_ww1_british_mandate_jordan.phphttp://www.eretzyisroel.org/~jkatz/jordan.htmlhttp://www.danielpipes.org/298/is-jordan-palestineLand Area Facts:
http://www.palestinefacts.org/pf_mandate_overview.phpI'll try and send you something about the Oslo Accords as soon as possible. I've got some important stuff to do.