One reason is that the European countries had superior military technology. They had guns, cannons, and other weapons that were more advanced than the weapons of the people they conquered. This gave them a military advantage that allowed them to defeat larger armies.
Another reason is that the European countries were able to divide and conquer the people they conquered. They would often play one group of people against another, and then use that division to their advantage.
Finally, the European countries were able to take advantage of the fact that the people they conquered were often not unified. They were often divided into different tribes or kingdoms, and this made it easier for the Europeans to conquer them.
In addition to these factors, the European countries were also able to benefit from the fact that they had a strong economy. This allowed them to fund their wars of conquest and to build up their empires.
As a result of these factors, the small European countries were able to control large empires in other continents. This had a profound impact on the world, and it shaped the course of history for centuries to come.