The Northern Kingdom consisting of 10 tribes was carried away by Assyria and in the fullness of time, they lost their identity as the house of Israel and became assimilated into all the nations of the world. The Bible refers to these 10 tribes by the following names.
1. The House of Israel (1kings 12:21, Jeremiah 31:31
2. The house of Joseph (1Kings 11:28)
3. Samaria (Hosea 7:1, 8:5-6, 13:16)
4. Ephraim (Hosea 4:17, 5:3, 7:1).
Intersted stuff. And Paul says all Israel will be saved. If you believe in the 2-house theology it may very well be that we "christians" are Ephraim and will be united with the House of Judah as prophecy predicts.
You certainly aren't going to be foolish enough to reject the written history concerning the Lost Tribes of Israel are you?