Sentence:Such an uneasy state of affairs existed until the fifth century, when the empire's Rhine barrier was breached, allowing a vast, mixed [e1]horde[/e1] of [e2]barbarians[/e2] to stream into Italy, thereby laying the groundwork for the kingdoms that would eventually come to dominate the European continent.
 e1: horde. 
 e2 : barbarians.
Answer: Member-Collection(e2,e1)