Yes, the 12 tribes of Israel always regathered and are not lost. James 1:1, Acts 26:7-8, Matt 19:28. See commentaries like Bengel's Gnomen. δώδεκα φυλαῖς, to the twelve tribes) of Israel.—διασπορᾷ, in their dispersion/diaspora) 1 Peter 1:1; Acts 8:1.
(ESV) Deuteronomy 28:25 “The LORD will cause you to be defeated before your enemies. You shall go out one way against them and flee seven ways before them. And you shall be a horror to all the kingdoms of the earth. If your outcasts are in the uttermost parts of heaven, from there the LORD your God will gather you, and from there he will take you.
Deuteronomy 30:4. If your outcasts are in the uttermost parts of heaven, from there the LORD your God will gather you, and from there he will take you.
From an article The Ten Lost Tribes Mystery of the Myth by Chuck Missler:
The "tribe of Judah" (2 Kings 17:18, et al.) is used idiomatically for
the Southern Kingdom.11 When encountering the tribal designations, it
is important to distinguish between the territories allocated to the
tribes and the people themselves.
The Northern Kingdom Falls
In 724 b.c. Shalmaneser V besieged Samaria for three years. King
Hoshea of Israel attempted to revolt against paying Assyrians annual
tribute money--a treaty with Pharaoh of Egypt did not help 12--and
Samaria, Jeroboam's capital, fell in 722 b.c. with Sargon II seizing
power in 721 b.c.
The Assyrians implemented their infamous policy of mixing conquered
peoples to keep them from organizing a revolt. Israelite captives were
mixed with Persians and others, and strangers from far-off lands were
resettled in Samaria. The resulting mixed, quasi-Jewish populations
became the "Samaritans."13 (You can read about this "fall" in 2 Kings
Not all from the Northern Kingdom were deported. Archaeologists have
uncovered annals of the Assyrian Sargon, in which he tells that he
carried away only 27,290 people and 50 chariots.14
Population estimates of the Northern Kingdom at that time range from
400,000 to 500,000; less than 1/20th were deported-- mostly the
leadership from the capital, Samaria. The rest of the Northern Kingdom
were taken by Assyria as slaves, which were a valuable commodity. (It
is difficult to view the Assyrians as careless enough to let their
captives wander off to Europe.)
When the Babylonians take over Assyria, the descendants of the "ten
tribes" were probably again commingled with the captives of Judah.
The Babylonians Take Over
When the Northern Kingdom went into captivity (722 b.c.), all 12
tribes were also represented in the south. When the Babylonians took
the Southern Kingdom into captivity (586 b.c.), members of all 12
tribes of Israel were involved. Isaiah, prophesying to Judah, refers
to them as the "House of Jacob, which are called by the name of
Israel..." (Isaiah 48:1; cf. vv. 12-14).
After the Babylonian captivity, the terms "Jew" and "Israelite" are
used interchangeably. Ezra calls the returning remnant "Jews" 8 times
and "Israel" 40 times. (Ezra also speaks of "all Israel": Ezra 2:70;
3:11; 8:35; 10:25, et al.) Nehemiah uses the term "Jew" 11 times and
"Israel" 22 times. Nehemiah too speaks of "all Israel" being back in
the land (Nehemiah 12:47). The remnant who returned from Babylon is
represented as "the nation" (Malachi 1:1, et al.).
The same is true in the New Testament. Our Lord is said to have
offered Himself to the nation, "the lost sheep of the house of Israel"
(Matthew 10:5-6; 15:24). Tribes other than Judah are mentioned
specifically in the New Testament as being represented in the land.15
Anna knew her tribal identity was of the tribe of Asher (Luke 2:36).
Paul knew he was of the tribe of Benjamin, a "Jew" and an "Israelite"
(Romans 11:1). The New Testament speaks of "Israel" 75 times and uses
the word "Jew" 174 times.16
At the Feast of Pentecost Peter cries, "Ye men of Judea" (Acts 2:14),
"ye men of Israel..." (Acts 2:22), and "All the house of Israel" (Acts
Regathered as One
Ezekiel 36 and 37, the Dry Bones Vision, declares that Judah (Jews)
and Israel (10 tribes) shall be joined as one in the regathering.17
This is true today. (The total physical descendants were not the
people to whom the promises were made [Romans 9:4-7].)
Footnotes from the article
11. Cf. 1 Kings 11:13, 32.
12. 2 Kings 18:2.
13. John 4:20-22.
14. Biblical Archaeology, VI, 1943, page 58.
15. Matthew 4:13, 15; Luke 2:36; Acts 4:36; Philipians 3:5; "the twelve tribes," Acts 26:7; James 1:1.
16. Acts 21:39; 22:3; Romans 11:1; 2 Corinthians 4 11:22; Philipians 3:5, etc.
17. Ezekiel 37:16-17, 21-22.