I decided to simulate a scenario using Europa Universalis 4 to see what the world could have looked like if the Roman Empire fell apart by 100 A.D. Check below to see map at the very end of this short blog.
The results were interesting, since without the Roman Empire, Europe never develops into a continent of superpowers, Christianity never dominates the world, and European colonization becomes far less prevalent. It also appears capitalism might not have developed in the same way, considering that the world markets seems fairly equal. There are no hyperpower states, and there are no 3rd world countries. I don’t think the slave trade occurred. The majority of the countries in the world are officially secular. Religious wars have not existed in a couple of centuries.
The strongest county is Satavahana, a former kingdom from the Indian subcontinent. The most developed city is Kurland-controlled Constantinople, with Persian Baghdad and Timbuktu not far behind. The largest religion is Druidism, since the British Isles were never invaded, and they were the only civilization to colonize. The Western Hemisphere, colonized by the Celtic British Isles (mostly the Irish), is entirely dominated by Druidism, when it isn’t irreligious.
North America of 2016 is dominated mostly by four large former Celtic colonies: The United States (won independence in 2015!), Louisiana, California, Mexico. The Iroquois still exist as a separate state. The West Indies are still Irish.
In South America, the former Celtic colony Brazil dominates the continent. Chile and Peru are strong. Some South American tribes still maintain independence. Overall, Latin America has none of the Spanish culture of the real world of 2016. Latin America is a mix of indigenous people and Celtic (mostly Irish) culture, including the Druid religion.
Europe is an interesting case. The Celtic Isles did not interact with continental Europe. Continental Europe ultimately was a tripartite power of Tunisia (originally from Northern Africa), Lombardy, and Kurland. Roman Catholicism and the Protestant Reformation were stopped early. This left three older versions of Christianity, which dominated only Europe: Coptic Christianity (mostly Tunisians), Orthodox Christianity (mostly Kurlanders), Arian Christianity (mostly Lombards). Minor countries include Greek controlled Crete, Etruscan Corsica and Sardinia, and a recent second incarnation of Rome, existing only in Italy. Persia also controls part of Europe. Coptic Tunisia is the only major country that is not officially secular. Tunisia has the world’s largest navy.
Africa is dominated by Tunisia in the North, Ethiopia in the East, Timbuktu (the powerhouse of the continent) in the West, and Botswana (recently free of Irish rule) in the South. Africa is a major economy, and Timbuktu has been a major world country since about the year 400 AD. Kongo, Sofala, and Persia also have a presence on the continent.
Asia consists predominantly of five major countries: Satavahana (Indian kingdom), Assam (another Indian kingdom, which controls Southeast Asia and Mongolia), Tibet (Tibet and China), Japan (Korea and Japan), and Persia (Iran and Middle East). The Mongols had dominated the region for most of the scenario, but they are long gone. They had absorbed China, but were themselves absorbed by Tibet. Siberia is split between the the Celtic nation Catuvellauni and Indian Satavahana. Brunei and Malacca are major forces in the South East Asian islands. Hindu is the dominant religion of Asia. The Middle East is entirely Persian, under Sunni Islam. Persia is the only Islamic state, and it is officially secular. Satavahana has the largest military and economy, but not significantly so.
Australia is split between Celtic Australia, Brunei Australia and Tindore Australia. Tindore occupy most of the nearby islands. Malacca controls New Zealand.
Lastly, Greenland was never colonized.
The alternate world in 2016: