Are you trying to be funny? Because that's hilarious.
Also, nobody (including the residents) considers the reservations in north america to be "nations". I'm guessing you've never actually been here.
A native American tribe is a nation, by definition [1]. Heck, the Canadians call theirs "First Nations".
A country requires sovereignty over some land, people, and international recognition. Without the last part, Sealand was a country. Funnily enough, depending on how strict you're with the criteria, some native American tribes are countries, and the US isn't always one due to reservations and states sovereignties.
1 - `a large body of people united by common descent, history, culture, or language, inhabiting a particular country or territory` Oxford English dictionary
A country needs to be self-governing, autonomous, and recognised by the majority of UN members. Taiwan isn't recognised by any country of note, including the US, so they fail the country test.