Originally, the possessive pronoun his was used twice in verse 13 (“and joined his people and became his subjects”), but there is no apparent antecedent. One’s first inclination is to assume that the text here is referring to Mosiah, the king in the land of Zarahemla. Mosiah is explicitly mentioned in the immediately following sentence (in verse 14): “Mosiah received them with joy”. The 1920 LDS edition cleared up this minor difficulty by replacing the first his with Mosiah’s (giving “and joined Mosiah’s people and became his subjects”). One might even consider the possibility that the original text here actually read Mosiah’s people and that early in the transmission of the text the following his in “and became his subjects” led to the replacement of Mosiah’s with his.
One problem with the 1920 emendation is that it created the only occurrence of “X’s people” in the entire Book of Mormon text. The original text has occurrences of only “the people of X”, with the following number of occurrences when X refers to an individual:
Nephi 141
(king) Limhi 23
Ammon 19
Zarahemla 11
Morionton 7
Shiz 6
Coriantumr 5
Mosiah 4
(king) Noah 4
Jared 3
(king) Lamoni 3
Antipus 2
Akish 1
Amalickiah 1
Amlici 1
Amulon 1
(the king) Jacob 1
Lehi 1
Moroni 1
Moronihah 1
Zemnarihah 1
Zeniff 1
Out of 238 cases, we always get “the people of X”, never “X’s people”. This result holds even when we extend X to include places, such as “the people of Gideon” in Alma 8:1 (that is, the people of the land Gideon) and “the people of Antiparah” in Alma 57:4 (that is, the people of the city Antiparah). For this construction involving people, the Book of Mormon text unexceptionally prefers the of-genitive rather than the s- genitive. This finding suggests that if Mosiah 22:13 were to be emended, a more consistent emendation would be to replace “his people” with “the people of Mosiah” (thus “they arrived in the land of Zarahemla and joined the people of Mosiah and became his subjects”). It should be noted that for such an emendation the antecedent for his would occur in a preceding postmodifying prepositional phrase (namely, “of Mosiah”); a similar example of such usage is found in the original text for the three-witness statement: “which is a record of the people of Nephi and also of the Lamanites his brethren”. Despite the theoretical possibility of “the people of Mosiah” here in Mosiah 22:13, it seems unlikely that the original text actually read this way since the change of “the people of Mosiah” to “his people” appears rather unlikely; the manuscripts and editions show no independent evidence for this kind of transmission error.
The consistent use of “the people of X” does not mean that the s-genitive never occurs at all in the Book of Mormon. We have, for instance, the following examples involving the names of individuals:
In no case does people serve as the head noun for a premodifying s-genitive.
It has been frequently observed that the Book of Mormon text often prefers the of-genitive, as in the phrases “the rod of iron” and “the plates of brass”, never “the iron rod” or “the brass plates” (although this is how English speakers today refer to these two objects). John A. Tvedtnes has identified such examples of the of-genitive as possible Hebraisms representing the construct state in Hebrew. See page 55 of his article “Hebraisms in the Book of Mormon: A Preliminary Survey”, Brigham Young University Studies 11/2 (1970): 50–60.
There are, however, other possible antecedents, at least theoretically, for the two his ’s in Mosiah 22:13. For instance, one could interpret the first his as meaning that the people of Limhi joined the people of Zarahemla: “they arrived in the land of Zarahemla and joined his people”. The problem, of course, is that by that time Zarahemla had been dead for about two generations. Thus the narrative itself makes it virtually impossible for the second his (in “and became his subjects”) to mean that the people of Limhi became Zarahemla’s subjects. David Calabro (personal communication) has suggested another possibility: the two instances of his may actually refer to king Benjamin, not king Mosiah. In the previous chapter, the original text actually refers to Benjamin rather than Mosiah as the king in Zarahemla:
In fact, in searching for an antecedent for the two his’s here in Mosiah 22:13, we find that Benjamin, not Mosiah, is the nearest preceding name that will work, although this potential antecedent is found some distance away, in Mosiah 21:28 (about one and a half manuscript pages earlier in the text). If the two his’s in Mosiah 22:13 refer to king Benjamin, then we can explain why the following verse (Mosiah 22:14) suddenly uses the name Mosiah rather than the expected pronominal he (“and it came to pass that Mosiah received them with joy”). King Benjamin, being in retirement, was not there to receive the people of Limhi. Even though Mosiah is the de facto king, king Benjamin is still alive and the people in the land of Zarahemla are still referred to as the people of king Benjamin, so that technically the people of Limhi joined king Benjamin’s people and were his subjects until Benjamin finally died. See under Mosiah 21:28 for further discussion regarding the use of Benjamin rather than Mosiah in that passage.
The critical text will therefore restore the earliest but difficult reading his people in Mosiah 22:13. One possible explanation for the difficult reading is that Mormon, in writing the text here, did not realize that he had provided no immediate antecedent for the two his’s that he wrote in verse 13. He had earlier mentioned that “the people of king Limhi … bent their course towards the land of Zarahemla / being led by Ammon and his brethren” (Mosiah 22:11). Mormon seems to have assumed that the reader remembers who is king in the land of Zarahemla, although the original text seems to treat both Benjamin and Mosiah as ruling kings until king Benjamin actually dies. Thus the two his’s in Mosiah 22:13 may refer to either king Benjamin or Mosiah, although textually the first works better.
Summary: Restore the original use of his in Mosiah 22:13 (“they arrived in the land of Zarahemla and joined his people”); there is no immediate antecedent for this his, but previous usage in the original text suggests that the his here actually refers to king Benjamin.