求短文why to say British history has been a history of invasion ?

why to say British history has been a history of invasion
British history has been a history of invasions.Before the first century AD Britain was made up of many tribal kingdoms of Celtic people:a powerful culture originating in central Europe.Then in 43AD Britain was invaded by the Roman empire,and England and Wales (though not Scotland or Ireland) became a part of the Roman empire for nearly 400 years.Two more groups of invaders were to come after the English:from the late 8th century on,raiders from Scandinavia,the ferocious Vikings,threatened Britain's shores.
Actually ,China ever be colony of Britain and the same as India.Maybe everyone know East Indian Company,which is a special company to rule India.All in all,British people have their trace all over the world,expanding and invading.