While we're on the subject of ethnic wrestling styles that evolved to similar states under different conditions, check out the similarities between Korean Ssireum wrestling and Icelandic Glima. Both are belt wrestling styles in which each contestant is required to give the opponent a waist and leg grip using a strap or harness. Korea and Iceland. Hmmm.
I wonder who were the first guys to say, "Hey, I'm bored. Let's tie ourselves together by the thigh and waist and wrestle!"