It is imagery that describes the merging of different cultures.
A crossroads is a place where two or more things come together. When she talks about the "continent at a crossroads", she is showing how the different cultures are coming together and merging. A crossroad is not a boundary that should be crossed. It is a place for crossings and coming together. It is not an actual boundary between continents. The crossroads is a strong word but it does not express an attitude of resentment and bitterness.