Evidence Central discusses the evidence for "Josh" as an authentic Semitic personal name.
Evidence Central, “Book of Mormon Evidence: Attestation of Josh," June 14, 2022, accessed July 5, 2023
ABSTRACT
The name Josh, which is presented in several Book of Mormon passages, is an attested Hebrew name.
EVIDENCE SUMMARY
The Name Josh in the Book of Mormon
Josh is the name of a city destroyed at the time of the death of Christ (3 Nephi 9:10) and the name of a commander of Nephite armies who was slain in the conflict at Cumorah (Mormon 6:14). Some early readers of the Book of Mormon considered this name to be clear evidence that the text was the product of a nineteenth-century writer. Yet Epigraphic discoveries from the ancient Near East made after the publication of the Book of Mormon provide evidence for the authenticity of this name.
Hebrew Inscriptions
The name Josh is a hypocoristic (shortened) form of the name Josiah, one of the last kings of Judah (Jeremiah 27:1). Robert Deutsch and Michael Heltzer note that “this hypocoristic name is not found in the OT but is known from epigraphic sources” from the time of the prophet Jeremiah when it was likely pronounced Yaush. It appears on two clay bullae (seals) and three ostraca (fragments of pottery) from the site of Lachish dating to 586 BC. Four persons mentioned in documents from the Jewish colony of Elephantine in Egypt are also identified by this name.
Conclusion
Once seen as sure evidence that the Book of Mormon was a modern work of fiction, it is now known that Josh is an authentic Hebrew name in a shortened form that would have been known by Israelites during the time of Lehi. Joseph Smith couldn’t have known this in 1829, however, because this form of the name was only discovered in the 20th century.