Land of Jashon

16) And it came to pass that in the three hundred and forty and fifth year the Nephites did begin to flee before the Lamanites; and they were pursued until they came even to the land of Jashon, before it was possible to stop them in their retreat.
17) And now, the city of Jashon was near the land where Ammaron had deposited the records unto the Lord, that they might not be destroyed. And behold I had gone according to the word of Ammaron, and taken the plates of Nephi, and did make a record according to the words of Ammaron.

Notes

North of the Land of Joshua. South of the Land of Shem. Near the land of Antum.

Since Antum was probably in the region north of the narrow neck of land, presumably the city of Jashon was as well.

Cross-References