Who were the "other sheep" referred to by Jesus as recorded in John 10:16 "And 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."?

3 Nephi 15:13-24

3 Nephi 15:13-24
13. And behold, 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.
16. 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.
20. And 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.
24. But behold, 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.