Hello!~ ^-^
I've heard that there are people who uses whistles to communicate to each other from a far distance for like up to 7 kilometers away.
Here's a video called '5 Strange Languages Still Spoken Today'
So... there are 5 languages here, but if you want to get to the whistling part, you may skip to (7:27) If you don't wanna skip, then you may continue on watching the whole video...

Well... not only from Spain, but also in Turkey from a village called Kuskoy

It's kinda amazing to use this sort of thing/technique/language... that way if you're lost somewhere on the mountains and there aren't any signals on your phone, we can still use whistles to communicate ....
I bet that your questions would be like "but what if those people who are lost on the mountains doesn't know how to whistle?" to me... I doubt that's going to happen... nowadays people from the world can whistle, but for those who can't... please, I beg you, practice whistling even if it frustrates you just keep practicing more and more until you get that sound out of you mouth =_='
For your kids... please teach them how to whistle too =_=' ...
Here's a video to convince you...

Isn't it greaaat!~
ahhh~ her sweet sound is so.... pleasant... ^-^

Well! that's it for today!
hope you enjoy one of the vids. even though, I know there are some people who'd get bored on videos which are documentaries and stuff like that =_=' ....

I'll see you later!
BYEE~ ^-^