For many years, Herbert Armstrong made his booklet, The United States and Britain in Prophecy, available free of charge. In it, he showed that the supposed "lost" ten tribes of Israel are still intact today, though they do not know their own identity! Briefly, he gives evidence that the two tribes of Joseph comprise the Anglo-Saxon, English-speaking countries of the world. Manasseh is now known as the United States, and Ephraim, the British Commonwealth: Britain, Canada, Australia, and New Zealand, as well as a part of South Africa.
The tribe of Judah (the Jews) is scattered among all nations, with a large number now living in the modern nation of Israel.
Putting together the information available from biblical and secular history as well as prophecy, we can be reasonably certain that other tribes are located as follows: Reuben—France; Dan—Republic of Ireland and a branch of Denmark that mixed with the northern tribes; Benjamin—Norway and Iceland; Zebulun—Holland (the Netherlands); Issachar—Finland; Gad—Switzerland; Asher—Belgium and Luxembourg; Naphtali—Sweden; Levi and Simeon—scattered among the other Israelite nations.
Of course, these identification are generalities. It should be noted that gentiles of many nations have also settled among these nations, especially in the big cities. In addition, national borders do not always constitute ethnic boundaries. However, national traits and histories suggest these identifications are accurate in the main.