10 things about Israel
Mostly from memory and some quick Google searches to check for mistakes, so there is a risk of some slight inaccuracies.
1. British Mandatory Palestine also included present-day Jordan
until they gave that part away (80% of the territory) to some king (can't remember his name) so it became Transjordan (now Jordan).
2. It can be argued that the creation of Transjordan was basically the creation of a state for the Palestinian Arabs
3. Later, the UN partition plan of the remaining 20% offered 55% to the Jews (including a big chunk of arid, uninhabited land)
4. Most Jews were happy with this and they said yes, but the Arabs said no
5. As soon as Israel was born, several Arab countries (the Arab League) attacked it in the hopes of gaining its land
6. Israel won and therefore got more territory than initially agreed upon in the UN partition plan
7. Transjordan, which had attacked Israel, occupied Judea and Samaria (The West Bank)
Since the Arabs said no to the partition plan, this territory didn't really belong to anybody.
8. In 1967, Israel launched a preemptive war against Egypt, Syria and Jordan: Israel took away the West Bank from Jordan and occupied the Sinai desert in Egypt
It gave the Sinai desert back to Egypt quite quickly as part of a peace deal. Jordan didn't want to have the West Bank back (I don't remember if they initially wanted it back or not, I just know that at some point they didn't want it anymore).
I think this is also when Israel took the Golan Heights from Syria? I believe the justification was that leaving it to the Syrians was much too dangerous considering the strategic location.
Oh, and this must be when Israel took Gaza from Egypt (which Egypt acquired in 1948 I think).