Who knew? Certainly not me.
Apparently Tibetan monks first used a form of yodeling to communicate. Marco Polo? brought that knowledge back with him to Western Europe, where it quickly became part of the alpine tradition. The American cowboy yodeling tradition — yippee-kay-yay, y’all! — came about because European immigrants brought the vocal style with them to the range. The cowboy yodeling patterns aren’t as varied as the European traditions. They tend to be slower and simpler, since they were primarily lullabies to calm the cows at night, and also to soothe the animals during milking.
You wouldn’t think the history of yodeling would be so fascinating, but it kind of is.