I'm going to assume that you're suffering from some ignorance on Amerindian culture. I personally know a lot about the Cherokee, so I'll use their national land as an example again:
The Cherokee nation occupied a stretch of land considerably larger than most European nations. It had provincial divisions and regional capitals (called "Mother Towns" by the Cherokee), and local, provincial, and a federal government. In addition, Columbus had nothing to do with your original post:
Your argument was essentially that Native Americans were so primitive that they had no concept of property or nationality. Now, while most NA peoples didn't have a system of personal land ownership divorced from the government (mostly because such ideas were pretty useless without the highly-complex international trade systems that led to the rise of the merchant class), they certainly had a sense of collective land ownership; namely, that this land is ours and you settlers can fuck right off with thinking that you can build your farms on our hunting territory or grab our villages.
As for nationality: calling them Native American
Nations isn't forcing a colonial concept on the natives. Get a Cherokee, a Miami, and a Creek in one room back then, and tell them they're all the same, you'd get bloodshed. Namely, they'd all stab
you for comparing them to their enemies, before stabbing each other.
Your gommie professor probably didn't think this would happen because the dialectical materialist view of history holds that national affiliations emerged as the result of the feudal system and that history is a deterministic straight line, so he saw the word "tribe", thought "
tribal hunting gathering ->Feudalism ->Rise of the Merchant Class ->Industrialism -> Late-Stage Capitalism ->Socialism ->Communism" and then stopped thinking.