In India there is a popular slogan:
East or west India is the best.
Is this slogan grammatically correct?
I know directions have the before them.
The east or the west India is the best.
Is this how the slogan should read?
I think it just needs a comma, or a dash.
Otherwise, it sounds like you are saying "East India or West India is the best." Also, "the" is understood in this phrase and is not needed.