In the Book of Mormon, the brother of Jared is the most prominent person in the account given in the beginning of the Book of Ether. Moriancumer is the name of the place that Jared and the people he was traveling with settled for a time. Some years after the publication of the Book of Mormon, Joseph Smith was residing in Kirtland, Ohio, when Reynolds Cahoon had a son. One day, when Smith was passing his door, Cahoon called him in and asked Smith to bless and name the baby. Smith did so and gave the boy the name of Mahonri Moriancumer. When Smith finished the blessing, he laid the child on the bed and told Cahoon that the "name I have given your son is the name of the brother of Jared; the Lord has just shown it to me." Cahoon heard Smith make that statement to his father, and that was the first time the name of the brother of Jared was known in the church.
According to the Book of Ether, Jared and his brother were present at the Tower of Babel. When the language of the people was confounded, Jared asked his brother to ask God not to confound their own language, that of their friends, and that of their immediate families.
Land of Moriancumer
After being granted to have their language not confounded, they asked to be led to where the Lord would have them go in the hope that it would be a choice land. They were led through the wilderness, across many waters, to the "great sea which divides the lands" and then dwelt in tents at the seashore for four years. They named the place that they had settled Moriancumer. The account relates that after four years, the Lord came to the brother of Jared and "chastened him because he remembered not to call upon the name of the Lord."
The brother of Jared was then instructed to build "barges" or boats. After building the boats, the brother of Jared worried about how the insides of the boats would be lit during their journey across the sea. The Lord told the brother of Jared that he should figure out a way to light the boats, and so the brother of Jared produced sixteen stones from molten rock, two for each ship, and they were white and clear, just like transparent glass. The brother of Jared then asked the Lord to touch each stone he had made so that they would shine in the darkness. The Lord touched each stone with his finger. The brother of Jared watched as the Lord did so and fell to the ground in fear. The Lord then revealed to the brother of Jared that he had seen his spirit, even as he would appear in the flesh. The brother of Jared was then told to write down what he saw in his own language, which no one would understand, and that his record would be revealed after Christ had been lifted upon the cross. The account continues to relate that the Jaredites, as they came to be known; boarded the boats; and were driven by the wind until they arrived at the "promised land."
In the Promised Land
When Jared became old, he and his brother gathered their descendants to count them: the brother of Jared had 22 descendants, the oldest male being named Pagag. Jared had four sons and eight daughters who are mentioned but unnamed. The Jaredite people wanted a king appointed. The brother of Jared was opposed but ultimately relented. After all of Mahonri's sons, and Jared's older sons refused the position, Jared's youngest son, Orihah, accepted. Jared and Mahonri died during the reign of Orihah.
Name
The name "Moriancumer" appears in the Book of Ether in the Book of Mormon, as a place that the people pitched their tents. Joseph Smith said that the full name and its connection to the brother of Jared were later revealed to him: Etymologies have been proposed but remain largely speculative. According to Daniel H. Ludlow, it is not clear why the name of the brother of Jared does not appear in the Book of Mormon. However, the following are possible reasons:
The brother of Jared may have omitted his name out of modesty.
The Book of Ether is clearly a family record of Jared, not the brother of Jared; Ether, the final writer and perhaps the abridger of the record, was a descendant of Jared and might naturally have emphasized the achievements of his direct ancestor rather than the brother of his ancestor.
Moroni may have omitted the name in his abridgment because of difficulty in translating the name into the Nephite language.
In the Roman practice of damnatio memoriae, names were intentionally removed from the record. Egyptian factions also wiped out names and statues of heretical rivals. In Ether 11:17-18, a direct descendant of the Brother of Jared, and rival king, is also not named.
