Balkanization

Balkanization is the fragmentation of a larger region or state into smaller regions or states, which may be hostile or uncooperative with one another. It is usually caused by differences of ethnicity, culture, and religion and some other factors such as past grievances. The term is pejorative when sponsored or encouraged by a sovereign third party, it has been used as an accusation against such third party nations. Controversially, the term is often used by voices for the status quo to underscore the dangers of acrimonious or runaway secessionism.
Or for others that don't understand, Balkanization is when One country's government / people start to form hatred towards its neighbouring country. For example Macedonia hates Bulgaria, Greece and for the most Albania. Bulgaria hates Macedonia, Greece, Turkey and Serbia. Serbia hates Albania / Kosova, Greece, Bulgaria, Bosnia and Croatia. Everyone hates Slovakia because they insist they are in the Balkans. Greece hates Macedonia, Serbia, Bulgaria, Turkey and Albania. Albania / Kosova hate Macedonia, Serbia, Montenegro, Greece, Bulgaria and Croatia and Bosnia think they are better than everyone so they hate everyone but themselves.

Balkanization
verb
past tense: Balkanized; past participle: Balkanized
divide (a region or body) into smaller mutually hostile states or groups.
"ambitious neighbours would snatch pieces of territory, Balkanizing the country"