In the world of the 20th and 21st centuries, the international system is composed mostly of independent states. Since the Treaty of Westphalia in the middle of the 17th century the European style state has come to dominate the international system. However, the rise of the European state also came at the same time as the conquest of most of the rest of the world and the incorporation of most of the world's peoples into European empires. It wasn't until the middle of the 20th century that most of the people in the world enjoyed the benefits of truly independent statehood.
It is also important to remember that before the European conquest other empires played an important role in world history.
The European expansion had already begun when Columbus "discovered" the "new world." As the maps below show, by the early 20th century most of the world's territory and peoples had come under European domination.
The leading European empire was the British. This map shows the British possessions circa 1900, an empire on which "the sun never set."
The world wars brought an end to the European empires. Most of the colonized peoples gained their independence within a decade or two of the end of World War II. The collapse of the Soviet Union wrote the final chapter in European political rule of non-European peoples.