http://en.wikipedia.org/wiki/Flag_of_Saudi_Arabia
Well, Saudi Arabia is the reference for almost more than 80% of Islamic population and the green color was the color of early Muslims therefore, the green was chosen to be the dominant color in the...
it says (la ellah ela Allah Mohammad rsol Allah)and it means no god but Allah and Mohammad is the messenger of Allah.
theres no saying on when it was invented but the latest modification was in 1972
same colour as ourss in Australia.