All the great prophets prophesied of the Messiah. The next verse says, how great a number had testified of these things. However, when we read the Old Testament, very few of these prophecies are plainly written. The most Messianic books are Isaiah, Psalms, and Zecharaiah. Although many of their prophecies give detailed descriptions of events that happened in the life of the Savior. None of these prophets were as plain as Nephi when he said, And I beheld the city of Nazareth; and in the city of Nazareth I beheld a virgin, and she was exceedingly fair and white…And I looked and beheld the virgin again, bearing a child in her arms. And the angel said unto me: Behold the Lamb of God, yea, even the Son of the Eternal Father! (1 Nephi 11:13,20-21) The Book of Mormon teaches that other Old Testament-era prophets were just as plain in their descriptions of the Messiah. These prophets, Zenos, Zenock, and Neum (see Book of Mormon Index) are not found in our Old Testament. This is another example of the loss of those plain and precious things as spoken of in 1 Nephi 13:28.
The chronology of the Book of Mormon is entirely based upon the statement that Lehi's departure marked 600 years before the coming of the Messiah. This dating system was followed until the beginning of the reign of the judges in 91 BC. The dating system from 91 BC to the coming of Christ was based on the reign of the judges, and the dating system after Christ's birth was reckoned after the year of his birth as we do today. Nonetheless, the dating system was followed exactly by the Nephites. Remember the unbelievers were scheduled to be put to death if the sign of the coming of the Son of God did not come as prophecied, Now it came to pass that the ninety and first year had passed away and it was six hundred years from the time that Lehi left Jerusalem…And it came to pass that he (Nephi) went out and bowed himself down upon the earth, and cried mightily to his God in behalf of his people, yea, those who were about to be destroyed because of their faith in the tradition of their fathers. And it came to pass that he cried mightily unto the Lord all that day; and behold, the voice of the Lord came unto him, saying: Lift up your head and be of good cheer; for behold, the time is at hand, and on this night shall the sign be given, and on the morrow come I into the world (3 Nephi 1:1,11-13).