What is the oldest nationality in the word?

Answer 1

China by name.....

But there is nobody left of any of the original peoples who occupied the lands from which they now draw their names.

The Sumerians left Sumer and migrated westwards... another nomadic people entered 1500 years later and their descendants now bear the name "Iraqi's". The same is true of the Indus Valley, and the people who inhabit that region as well as China and South America where the Toltecs used to live.