There are hundreds of strains of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus bacteria, that are used to make "sour milk" (or yogurt). I don't really care who invented what and when, I just enjoy the great variety of natural products, and I really hate the surrogates produced by the big brands like Danone and Nestle. At the end of the day, it is a matter of taste, but as a Bulgarian I prefer natural Bulgarian "кисело мялко" that could be found only in selected shops or in small villages around the country, because it is more sour, naturally thick, with >5% natural fat. There are similar products all over the Balkans and also in Iran, but they have different taste and texture, I guess depending on the different strains used for the fermentation and many other factors. I've traveled to more than 50 countries on 4 continents in the last 30 years, and I could say one thing - just don't consume the "branded" surrogates, that pretend to be "something", if you haven't tasted the real thing :-) I guess the same is true for every food - just last week I've purchased like 5 different brands of Dijon mustard in Dubai...OMG, none of them was even remotely close to what a Dijon mustard is...

Most Bulgarians eat "кисело мляко" (sour milk) every day, some mix it with water + some salt to make "айрян", which is a drink :-) The so called "yogurt" has nothing to do with "кисело мялко". I am not saying that yogurt is bad, it's just some powder milk + emulgators + sweeteners, produced by companies like Danone, Nestle etc. We have hundreds of brands, but only a few produce the "real deal"...free market, you know :-)