While translating the Book of Mormon plates into English, Joseph Smith noticed the record mentioned the walls of Jerusalem. He asked his wife if Jerusalem had walls and Emma replied that they did. Perhaps the prophet had read these words in First Nephi 4:4:
. . . nevertheless they did follow me up until we came without the walls of Jerusalem.
The modern English usage of “without” usually relates to words like “absence” or “omission” or “avoidance.” But in earlier generations of English speakers, it was often used as the opposite of “within,” meaning “outside of.” This is the meaning of “without” in an LDS sacrament hymn:
There is a green hill far away, Without a city wall.
This is also the meaning in First Nephi, for Jerusalem did indeed have walls.