The Book of Mormon does not specifically give the time of the destruction of the Jaredites. By the time of Limhi, they had been dead long enough that their swords had decayed, the hilts thereof have perished, and the blades thereof were cankered with rust (v. 11). On the other hand, they had breastplates which were still in good condition (v. 11). Coriantumr had stayed with the Mulekites in Zarahemla for 9 months signifying that the Jaredites were still alive after the Nephites and Mulekites arrived (Omni 1:21). Nevertheless, the Jaredites were wise enough to preserve their record on gold plates and provide a Urim and Thummim for the interpretation of their record.
The geography of the Book of Mormon is not that important, but it is helpful to have a mental map for the next several chapters. This passage gives us a clue to the relationship between the city of Lehi-Nephi, Zarahemla, and the land of the Jaredites. This small band of forty-three people would have headed north to find Zarahemla. That they found the land of the Jaredites is not surprising because the Jaredites were known to inhabit the lands of the north (Alma 22:29-30). Alma 22 demonstrates that the land of the Jaredites was farther north than was Zarahemla.