Bulgarian music makes extensive use of time signatures with odd numbers and is an interesting combination of rhythms.
Dancers learn Bulgarian/Balkan rhythms as a combination of "quick-slow" beats. The person teaching the dancing will have the students clap the rhythm before teaching the footwork. The point of this is to feel comfortable with the beat before learning the dance.
To get an idea of the rhythm of the rachenitsa, say the words "apple apple pineapple." The time signature is in 7/8, for you music theorists out there (7 beats to the measure, the eighth note gets the beat).
Here's an example of a rachenitsa from a Bulgarian teaching video. This is the couple version of the dance Shopska Rachenitsa, and at the end you'll see why this is a dance with a sense of humor :) This reminds me of a courtship dance, which it probably is:
Rachenitsa comes in many "flavors" and because of the diversity of the different folklore regions of Bulgaria, there are lots of them. Here is one on my favorites, by the composer, Petko Stainov, of a Thracian rachenitsa for orchestra, which sounds more like classical music than Bulgarian folk, but beautiful nonetheless:
This last video is a dance called Brestaska Rachenitsa, which is rachenitsa for the rest of us, performed by a group from the United States. These are people who dance on Friday (or any other night of the week), for fun and exercise, like myself.
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