1 Nephi 5:11–13

11 And he beheld that they did contain the five books of Moses, which gave an account of the creation of the world, and also of Adam and Eve, who were our first parents;

12 And also a record of the Jews from the beginning, even down to the commencement of the reign of Zedekiah, king of Judah;

13 And also the prophecies of the holy prophets, from the beginning, even down to the commencement of the reign of Zedekiah; and also many prophecies which have been spoken by the mouth of Jeremiah.

These brass plates, in many ways, were similar to our Old Testament. They contained the books of Moses, which is something each tribe of probably had a record of, as well as a history of the Jews and prophesies and writings of the prophets. My guess is that each tribe of Israel kept an official record, each one containing these items. The things that would differ between the tribes is which prophets to include. They probably kept the record of the main prophet plus any others that pertained to that tribe specifically. In verse 14 we’ll see that the plates also contained a genealogy of the tribe of Joseph, which means that if my theory is right, each tribe also kept a genealogy of its own. It would be impossible to keep everybody’s genealogy on one official record, so it’s probably a royal genealogy, which would indicate that Lehi was in the royal line.

• 1 Nephi 19:23