This is a topic that many readers will be familiar with. It circulates widely on the web. In a nutshell, it’s the notion that the ten tribes of Israel (the northern kingdom of the divided monarchy in ancient Israelite history) that were deported and scattered by the Assyrians eventually migrated in some fashion to the British Isles. The British colonists who came to America are their descendants, and so Britain / America was / is the new Israel. In case some of you have not heard of this idea, here is a summary (see the Wikipedia entry as well).
Criticisms and debunkings of the idea have been around since its genesis. I’d like to direct your attention to a recent lengthy expose on the subject. I know the author (Greg Doudna). Greg is a published expert on the Dead Sea scrolls. His religious background was in circles that promote the lost ten tribes mythology. Hence his interest and this book (the book’s title is awful, leaving the reader no clue as to the subject matter).