Simplify the following text for a Grade 10 native English-speaking person.
Original: The British Invasion is a term used to describe the large number of rock and roll , beat , rock and pop performers from the United Kingdom who became popular in the United States during the period from 1964 through 1966 .
Simplified: The British Invasion is an event where many rock and roll , beat , and pop bands from the United Kingdom became very popular in the United States , Australia , and Canada .