This is right between the volcanos of Popocatepetl (shown)and Iztlacihuatl, 2 of the 5 highest peaks in Mexico. Cortes marched thorough here along with a few hundred Spaniards and several thousand native allies on his way to Tenochtitlan which he conquered some months later. The pass is actually closed now and has been for the last fifteen years, as I found out later, because the Popo coughs up colums of smoke an ashes from time to time. It`s name means mountain that smokes in nauhatl.