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>>Yes, I knew that... Thanks for the further explanation...
>>It's interesting for me to find out the Russian/English proverbs analogues. Now, the question is: which culture invented this first?
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>Probably the Huns! They were into horses, right?

Could be the Gypsies (aka Roma). There are two general professions among them - musicians and horse traders. Though I have seen the latter becoming used car dealers.