Simplify the following text for a Grade 5 native English-speaking person.
Original: Modern art was introduced to the United States with the Armory Show in 1913 and through European artists who moved to the U.S. during World War I.
Simplified: Modern art was introduced to the United States in 1913 and through European artists who moved to the U.S. during World War I. It was only after World War II , however , that the U.S. became the focal point of new artistic movements .