Defensive walls around Nephite cities were not uncommon (see Alma 50:6). Jerry Ainsworth notes that according to local people in the area of Palenque, remains of a huge earthen wall--may miles in circumference--exist around the area to this day. One can see eroded parts of that wall stretching for miles along the highway between Emiliano Zapata and Villahermosa. From the sheer size of these remains, one could postulate that there may have existed a wall around that area as much as a hundred miles in circumference.
The Spanish dictionary defines palenque as "a wooden barrier or stockade." A wooden barrier apparently at one time encircled the area of Palenque. A town in the same area, Palizada, has a similar name. Palizada means "a place fenced with sticks" or "a wall of timber." [Jerry L. Ainsworth, The Lives and Travels of Mormon and Moroni, pp. 108, 110]
Alma 50:6 Moroni did prepare strongholds . . . round about every city in all the land (Illustration): Defensive breastwork of timber, the type that surrounded the Book of Mormon city of Bountiful. Drawing by Terry Rutledge. [Jerry L. Ainsworth, The Lives and Travels of Mormon and Moroni, p. 108]