How much land do the aborigines actually own in the mountains?

A trivia question here. How much land do the aborigines actually own in the mountains?

They don’t actually own all the mountain land in central/southern taiwan… do they?

Or should I say… are all the good habitable parts of taiwanese mountains owned by aboriginals because i was told that aboriginals are not allowed to rent or sell their land to han chinese?

but since i am not a han chinese, can i then rent or buy the land from the aboriginals?