Lets go back to Native Americans or Polynesians before they ever came into contact with the Europeans. none of them knew anything about God, Jesus, Abraham, Moses or Mohammad. there have been many civilizations in the past that were never sent a Divine scripture or prophet.
according to muslims, a prophet has been sent to every civilization. but that is simply not true. why is it that there is no evidence of such prophets being sent to Native Americans? if Islam is the true religion, why did God not send them with the same message? why did God/Allah keep this truth away from native Americans?
The answer to your question is found in Mormonism. While we believe that the Bible is the word of God, we believe that God has said much more than has been assembled in that single volume and that He is still not through speaking to us. The Bible, of course, contains both the Old Testament and the New Testament, the New Testament being a witness to the divine mission of Jesus Christ. The Book of Mormon is yet
another testament of Jesus Christ,
another witness to His divinity and to His role as Savior of the world. It is the history, both religious and secular of several groups of people whom we believe we led by God to the American continent in ancient times. By far the largest portion of the book describes two civilizations, the Nephites and the Lamanites, who were both descendents of the House of Israel, and who lived on this continent between about 600 B.C. and 400 A.D. (Joseph Smith, I should mention at this time, was not the writer but the translator.)
When Jesus Christ spoke to his followers in the Holy Land, He is recorded in the Gospel of John as having 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. Note: He said they would hear His voice, not merely His message as it would be relayed by others. He also said that His own personal mission was only to the lost sheep of the house of Israel. So who were the other sheep of whom He spoke, people who were evidently not living in the Holy Land but who were, at the same time, of the house of Israel? We believe they were the people whose story is told in the Book of Mormon. After Christs resurrection, he stayed among his Apostles and others for a time. But, according to the Book of Mormon, before He returned to heaven where He now awaits the time of His Second Coming, He visited the people of ancient America. He established His Church here, teaching exactly the same gospel of love, forgiveness and mercy He had taught in the Holy Land.
The Book of Mormon is an account of a 1000-year history of some of the people of ancient America, and includes a number of chapters which describe in some detail Jesus Christs ministry among those people. It does not contradict or supplant anything in the Bible. Rather it complements and clarifies many of the doctrines to which the Bible alludes but is not entirely clear. Its purpose is literally to prove the Bible to be true, and, as stated on the title page of the book is to the convincing of the Jew and Gentile that Jesus is the Christ.
Here are a few verses from it, addressing the topic of your OP:
From 2 Nephi 29:7-11
"Know ye not that there are more nations than one? Know ye not that I, the Lord your God, have created all men, and that I remember those who are upon the isles of the sea; and that I rule in the heavens above and in the earth beneath; and I bring forth my word unto the children of men, yea, even upon all the nations of the earth?
Wherefore murmur ye, because that ye shall receive more of my word? Know ye not that the testimony of two nations is a witness unto you that I am God, that I remember one nation like unto another? Wherefore, I speak the same words unto one nation like unto another. And when the two nations shall run together the testimony of the two nations shall run together also.
And I do this that I may prove unto many that I am the same yesterday, today, and forever; and that I speak forth my words according to mine own pleasure. And because that I have spoken one word ye need not suppose that I cannot speak another; for my work is not yet finished; neither shall it be until the end of man, neither from that time henceforth and forever.
Wherefore, because that ye have a Bible ye need not suppose that it contains all my words; neither need ye suppose that I have not caused more to be written.
For I command all men, both in the east and in the west, and in the north, and in the south, and in the islands of the sea, that they shall write the words which I speak unto them; for out of the books which shall be written I will judge the world, every man according to their works, according to that which is written."