To be genocide, doesn't;'t it have to be purposeful?
The OP claims it might have been genocide due to the death toll, but what defines the term is extermination intent, not how bad the results were.
The US government position on the Trail of Tears is that while it has the demographic equivalent of a mass killing, it wasn't a genocide since the goal was to move the Indians west, not kill them. They got killed off not by bullets or biological warfare, but because the government was like "and in seven days, we're moving all of you. No, we don't have any medicine, blankets, or fresh water for any of you. Yeah, we know plenty of you adopted White man's agriculture (They were called the Five Civilized Tribes) and don't actually know how to survive in the wilderness like your ancestors. We don't care. We're not trying to kill you, we just want your land"