Where is Bilakh ( the equivalent of giving somebody the finger in Iran) coming from?

One of my British colleagues sent out this email regarding the origins of giving the middle finger in west, read it.

Before the Battle of Agincourt in 1415, the French, anticipating victory over the English, proposed to cut off the middle finger of all captured English soldiers. Without the middle finger it would be impossible to draw the renowned English longbow and therefore they would be incapable of fighting in the future. This famous weapon was made of the native English Yew tree, and the act of drawing the longbow was known as “plucking the yew” (or “pluck yew”).
Much to the bewilderment of the French, the English won a major upset and began mocking the French by waving their middle fingers at the defeated French, saying, “See, we can still pluck yew! PLUCK YEW!”
Since ‘pluck yew’ is rather difficult to say, the difficult consonant cluster at the beginning has gradually changed to a labiodental fricative 'F', and thus the words often used in conjunction with the one-finger-salute!
It is also because of the pheasant feathers on the arrows used with the longbow that the symbolic gesture is known as “giving the bird.

I replied the email and explained how in Iran the thumbs up is conceived the same as middle finger in west but I had no story for it.
Now I am thinking where our Bilakh is coming from, I guess it has something to do with the secound world war and the invasion of Iran by American and British troops. I read something about Bruce Willis travelling to Iraq and his comments about how well he had been welcomed by Iraqi people who had shown him lots of thumbs up. I don't know if in Iraq holding thumbs up is the same as in Iran?