Found this interesting article that traces the origins of Pierogi back to China and Italy.
It also discusses the regional variations of pierogi in Poland with meat filled pierogi more of a city thing.
The cheese pierogi being more of a rural dish ...
"They are known in Poland as ruskie pierogi (Ruthenian another name for Ukrainian), because they are believed to have originated in the Lwów region and are usually served with a garnish or fried fatback nuggets (skwarki)."
Well, really ... fried fatback nuggets ... ancient Polish genes are going 'yum' in my head.
Potato and onion filings were the creation of poverty and are said to orginate in the province of Galicja which was once ruled by Austria.
Fruit pierogi are summer pierogi.
The article was originally published in 2003 and mentiones that pierogi were making a come back in of all places ... Poland.
Any way, here's the link.
Who knew .. invading Mongolian hordes ... it was a good thing ... pierogi-wise.