In Alma 15:18 it says that "he [Alma] took Amulek and came over to the land of Zarahemla, and took him to his own house . . ." The phrase "came over" might indicate that Alma and Amulek had to come over something in order to reach Zarahemla. Previously we have assumed elevation, so they might have had to cross an elevated mountain ridge or range. On the other hand, "come over" might refer to a body of water such as the Sidon river. We might wonder why no mention is made of following along the river Sidon? A Chiapas Depression setting gives some perspective. According to the geographical theory of John Sorenson (Chiapas Depression = general land of Zarahemla), the standard sensible route from Sidom/Chiapa de Corzo would indeed have been "over" via the highlands, east of rather than along the river. The higher route provided smoother traveling and was much cooler. Movement alongside the river would have been interrupted by bluffs and ravines or would have passed through difficult Angostura canyon. Besides, the hot climate at the bottom of the confined valley would cause discomfort. Once more the modern highway, seeking out the easier route, parallels the ancient way up through the highlands. Alma and Amulek would have ascended from Chiapa de Corzo to the 7,000 foot level, around the present day city of San Cristobal de Las Casas, an area that archaeological investigation shows was settled only lightly if at all in their time. They would press on through the Teopisca Valley before dropping down to the river just downstream from Zarahemla. [John L. Sorenson, An Ancient American Setting for the Book of Mormon, p. 206] [See illustration]
Note* In interesting note is that in the Chiapas Depression setting that has been followed so far, by the time Alma reached the land of Sidom, or the present day city of Chiapa de Corzo, he would have almost completed a missionary circuit around the central depression of Chiapas. The only apparent thing left was his final journey home. [Alan C. Miner, Personal Notes]