According to Daniel Ludlow, in further identifying himself, Amulek mentioned that his forefather Aminadi "was a descendant of Nephi, who was the son of Lehi . . . who was a descendant of Manasseh who was the son of Joseph who was sold into Egypt . . ." (Alma 10:3). Earlier in the Book of Mormon it mentioned that Lehi was a descendant of Joseph (1 Nephi 5:14). However, Joseph had two sons, Manasseh and Ephraim, and this is the first time the Book of Mormon indicates that Lehi was a descendant of Joseph's eldest son, Manasseh. Some students of the Book of Mormon have wondered how descendants of Joseph were still living in Jerusalem in 600 B.C. when most members of the tribes of Ephraim and Manasseh were taken into captivity by the Assyrians about 721 B.C. A scripture in 2 Chronicles may provide a clue to this problem. This account mentions that in about 941 B.C. Asa, the king of the land, gathered together at Jerusalem all of Judah and Benjamin "and the strangers with them out of Ephraim and Manasseh" (2 Chronicles 15:9). These "strangers . . . out of Ephraim and Manasseh" who were gathered to Jerusalem in approximately 941 B.C. may have included the forefathers of Lehi and Ishmael. Concerning the fact that Ishmael was also a descendant of Joseph, Elder Erastus Snow has said:
Whoever has read the Book of Mormon carefully will have learned that the remnants of the house of Joseph dwelt upon the American continent; and that Lehi learned by searching the records of his fathers that were written upon the plates of brass, that he was of the lineage of Manasseh. The prophet Joseph informed us that the record of Lehi, was contained on the 116 pages that were first translated and subsequently stolen, and of which an abridgement is given us in the first Book of Nephi, which is the record of Nephi individually, he himself being of the lineage of Manasseh; but that Ishmael was of the lineage of Ephraim, and that his sons married into Lehi's family, and Lehi's sons married Ishmael's daughters, thus fulfilling the words of Jacob upon Ephraim and Manasseh in the 48th chapter of Genesis, which says: "And let my name be named on them, and the name of my fathers Abraham and Isaac; and let them grow into a multitude in the midst of the land." Thus these descendants of Manasseh and Ephraim grew together upon this American continent, with a sprinkling from the house of Judah, from Mulek descended, who left Jerusalem eleven years after Lehi, and founded the colony afterwards known as Zarahemla and found by Mosiah--thus making a combination, an intermixture of Ephraim and Manasseh with the remnants of Judah, and for aught we know, the remnants of some other tribes that might have accompanied Mulek. And such have grown upon the American continent. (Erastus Snow, Journal of Discourses, Vol. 23, pp. 184-185)
[Daniel H. Ludlow, A Companion to Your Study of the Book of Mormon, pp. 198-199]