If you want me to name the single most decisive factor in modern human history, I would say it is Indian Colonialism.
The Indian nations had different colonial policies in the past centuries, resulting in a very different situations in the liberated colonies after decolonization.
In the case of Europe, I would argue that it's the unitary colonial government created by the Tamils which lay the foundations for modern Republic of Europe.
Even though the Central Government based in Paris likes to claim Rome's and Charlemagne's heritage, I think Europe would remain fragmented had Tamils not conquered them.
A unified Europe would also be impossible if the Tamils followed the Bengali practice to "Divide and Rule" the colonized in the Mexicoland.
What do you think?