"Julius Caesar ruled over territory in present-day Italy, Tunisia, Spain, Turkey, (...etc)" is a perfectly normal sentence.
1) ruled is in past tense
2) "over territory in" establishing geographical context
The title starts with "People in present-day Austria" (implies the people there now) then switches to past tense and adds 2700 years ago.
No, I don't think it implies this. That would just be "people in Austria"; or if you want to make the presentness explicit, "people in Austria now".
> then switches to past tense
It's not a switch. "People in present-day Austria" doesn't have any tense (there are no verbs).
Honestly, I don't care what you think. It confused me. What more do you want from me?