Since the start the Protestant Revolution in Europe, the warring tribes of the world are amalgamating into distinct nations (who seems to go to war regardless!).
In the 17th century, German princes began breaking the iron grip of the Roman Catholic Church over their kingdoms by whipping up the Protestant revolt. Rome gave in, as it was timely compensated by gold and lands from the central and south Americas.
In the 19th century, the wars of nationalism came to Catholic Europe and Americas. Despite the Protestant model of government, the new nations continued to practise Roman Catholicism.
In the early 20th century, Middle Eastern and Muslim countries came into the existence from the dissolution of the Othmania Sultanat (Ottoman Empire). This was mostly a colonial process. While atheism was the theme of this century, return to Islam became an aspiration for Muslims.
As decolonisation began, India and China managed to create a larger tent for their many tribes to live under. This was done by borrowing concepts of Socialism and Communism.
In the 21st century, the authoritarian Russia is keen to keep its empire by guiding and protecting the Orthodox Catholic Church. A group of Indians are working hard to make Hinduism into a central, universal religion. Though China affirms its faith in Communist ideology, it uses this modern concept to achieve its ancient status of an unchallenged heavenly kingdom.
Check out the countries that interest me most in this section.