Not much can be read from toponyms: they get recycled and reused. Consider the following:
The Roman town of Londonum collapsed entirely, but was refounded in the 9th century. There is no continuity between Londonum and modern London
The Commonwealth of Massachusetts is not a nation dominated by the Massachusett Indians. Nor is Iowa dominaed by the Ioway.
Some names describe dominant geological features that would likely remain regardless of the political situation: Mississippi and Missouri, Rhineland.
Some names will fall into disuse, even if a continuity can be drawn between regimes, like Zaire.
ETA: many European cities have a "street of the Jews" where, in fact, no Jews live. It merely memorializes the location of the ghetto.