With apologies to Douglas Adams:
Iran is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to Iran.
Think of France.
Then think of Spain.
Then think of Germany.
Think of all of them together and you are starting to get your head around the size of Iran.