What's happened to the kingdom of Israel and Judah?

according to the Bible the kingdom of Israel didn't survive and they disappeared and that's the reason many people claim to be jewish and descedents of the 12 tribes of Israel but where were they? where did they go? and the king of Judah or Judea survived to the dominations and they were exiled to Babylon but they survived why is that? according to the Bible when they got back to Israel, they found people living in that region according to some people they were the palestinians or samaritans or who were those living after the exile of people of Israel and Judah?