Genealogy /
THE MEANING AND RESEARCH OF MY POLISH LAST NAME, SURNAME? [4500]
Would many Poles in modern day eastern Poland descend from Ruthenians,
You need to be aware that modern's Poland borders had been moved significantly to the west.
It means that what you term eastern Poland today had been a central Poland about (approximately) 70 years ago.
Was there a population in a Poland's east historically that would be a transitioning people's where Lechites and Ruthenians over lap?
- Lechties is no an ethnical term, it is not a term that had been used as far as we can tell - historically. It is a part of the national mythology created in the 19th century by idealistic writers, poets and historians while Poland had no state.
- Ruthenias is a name for a diverse group of people that had been living within borders of the Poland-Lithuanian Union. Their main characteristic was their religion-eastern-orthodoxy. It means that there had been a lot of mixing and honesty your question in the historical context makes no sense. If you're after some PURE DNA marker - you're wasting your time.
The Belarusan and Ukrainian languages were highly influenced by Polish. Polish less so by either.
So much so that I question if those are really languages rather than a local version of the Polish language.