The first sentence of the Wiki article for 'smoke signal' is this: The smoke signal is one of the oldest forms of long-distance communication.



( Image of a 1905 painting by Frederic Remington, via Wikimedia Commons.
http://en.wikipedia.org/wiki/File:Frederic_Remington_smoke_signal.jpg )

Native American Indians come to mind with the term 'smoke signal', but communicating this way has been used by other cultures, too. I like the thought of the Chinese on The Great Wall passing messages at night some 400 or so miles along the wall, station to station. You gotta wonder though, if, like with kids playing telephone, the message that reaches the end of the wall isn't a lot different from the one that was started at the beginning!