The great migration was the movement of some six million African Americans from rural areas of the southern states of the United States to urban areas in the Northern states between 1916 and 1970
Geographic locations, based on where they were, mountains, streams, rivers, etc.
The difficulty arises from few different factors:
- Culture
- Religion
- Geography
- Politics
Europe and Asia are actually one continent, but it has been 'divided' into two continents because of the reasons mentioned above.
Geographically are used some points as zone of separation, but there's still discussion which of the two prevailing is the most relevant.
From cultural and religious point of view Europe and Asia are mostly divided at the border of the Christian and Muslim world, but not totally, which also makes confusions.
And for last we have the political factor, where the geopolitical interest makes superficial borders as zones of interest, and thus making imaginary border lines.
The answer is to establish rules that a government must follow
