3 Nephi 16

As the Savior seem to conclude man of the "higher" principles, doctrines, commandments and ordinance that He taught during his mortal ministry to those in the Americas, He summarized -

"Behold, I am the law, and the light. Look unto me, and endure to the end, and ye shall live; for unto him that endureth to the end will I give eternal life.
10 Behold, I have given unto you the commandments; therefore keep my commandments..."  (Book of Mormon  3 Nephi 15:9 - 10)

In this summary, He added to the doctrine of Christ (just as Nephi taught) the last component of that doctrine - "endure to the end".  This doctrinal component then is also essential for eternal life.

And then the Savior turns to His disciples or His priesthood leaders and teaches them -

"...this is the land of your inheritance; and the Father hath given it unto you.
14 And not at any time hath the Father given me commandment that I should tell it unto your brethren at Jerusalem.
15 Neither at any time hath the Father given me commandment that I should tell unto them concerning the other tribes of the house of Israel, whom the Father hath led away out of the land."  (Book of Mormon   3 Nephi 15:13 - 15)

First, we witness priesthood organization.  Everyone has a priesthood or "file" leader, even the Savior.  It is obvious that the Savior only does those things that the Father commands.  It is here that we learn the Savior was commanded by the Father during His mortal ministry to say -

"...other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd."  (New Testament   John 10:16)

The Savior then explains to those in the Americas -

"This much did the Father command me, that I should tell unto them:


17 That other sheep I have which are not of this fold; them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd.
18 And now, because of stiffneckedness and unbelief they understood not my word; therefore I was commanded to say no more of the Father concerning this thing unto them.
19 But, verily, I say unto you that the Father hath commanded me, and I tell it unto you, that ye were separated from among them because of their iniquity; therefore it is because of their iniquity that they know not of you."  (Book of Mormon   3 Nephi 15:16 - 19)

And then, probably with some surprise to His disciples -

"...verily, I say unto you again that the other tribes hath the Father separated from them; and it is because of their iniquity that they know not of them.
21 And verily I say unto you, that ye are they of whom I said: Other sheep I have which are not of this fold; them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd.
22 And they understood me not, for they supposed it had been the Gentiles; for they understood not that the Gentiles should be converted through their preaching.
23 And they understood me not that I said they shall hear my voice; and they understood me not that the Gentiles should not at any time hear my voice—that I should not manifest myself unto them save it were by the Holy Ghost."  (Book of Mormon  3 Nephi 15:20 - 23)

Therefore -

"...ye have both heard my voice, and seen me; and ye are my sheep, and ye are numbered among those whom the Father hath given me."  (Book of Mormon  3 Nephi 15:24)

Who knows how many groups of Israel that were also visited and kept a record.