Alternative versions of Superman establish a new continuity for DC, affecting not only Superman, but all of the DC Comics characters. The versions of Superman from this time period are traditionally divided into three main periods. The first version of Superman began being published by DC Comics in 1938 appearing in "Action Comics" #1. To explain discrepancies in the aging of Superman across several decades, his earliest stories were retroactively portrayed as having taken place on an alternative world called Earth-Two. These stories take place from 1938 until the late 1950s, although the exact dividing line is unclear and some stories happened identically to
For Tomorrow (comics) an alternate universe version of the character. The "real" General Zod appears for the "first" time in the "" arc, which ran in "Action Comics" in 2006. The idea of Superman moving to a Peru jungle to construct a new Fortress of Solitude is a major story arc elaborated on prior to the events of "Identity Crisis" and "Infinite Crisis". He does not return to the Arctic Circle to rebuild the destroyed Fortress until the "One Year Later" arc "". In addition, Equus returns in "Countdown to Final Crisis" #36 (2007), in which he is trying to instigate a strike