A lot of French and Italian recipes I find begin with these ingredients. I also learned variations exist for German, Spanish, Polish, etc cuisines, too, usually subbing out one ingredient for another. For example, bell pepper, parsnip, leek, and more. I read somewhere, probably hearsay, that poor families who could not afford meat in antiquity used these ingredients as a very rough approximate for the taste of meat.

I know they're used to build up flavors early on in dishes; the impact a mirepoix has on a dish is hard to quantify, I just know it's sorely missed when absent. I'm mostly curious how such a technique could appear almost universally in so many forms of European cuisine, and maybe the history of this cooking step. Did it originate in one place and spread or individually "discovered" in many regions at once?