The presence of aliens, are we thinking shortly on aliens to produce radio waves?

As SETI combs the sky for advanced civilizations from radio waves do we actually know any civilization that is stuck in a time of medieval technology? how does science count out the aliens that has reached this age of progression from the the ones who account to reach to other lifeforms in the cosmos?

via International Skeptics Forum https://ift.tt/2pCWS0k