I've met folks that descend from the Zapotec in southern Mexico, and they still use whistling language to talk to each other across mountain valleys.

There are still people speaking a whisking language in the south-west of France[1], not many but it's being taught in school there to preserve it[2]

[1]: https://fr.wikipedia.org/wiki/Langage_siffl%C3%A9_d%27Aas

[2]: https://www.dailymotion.com/video/x4lxhsi