Diversity fails when it becomes policy or rather, a goal. Empires, although not explicitly stated, tend to strive for diversity. This is so because when expanding terrority, it is rare that the indigenous population is replaced completely by the conquering lands. All too often, an Empire tends to absorb peoples as it expands. They do tend to force aherence to their culture. While this is successful to a point, it tends to be rather difficult to erase generations of ethnic and cultural identity. Thus, diversity as a goal fails.