 The purpose for the narrator losing his memory is. . .
He was Yandro, the Stranger of the Prophecy—and he found that he was destined to fight both sides. Words formed themselves on my thick tongue, words that must have been spoken by so many reviving unfortunates through the ages: "Where am I?" It is as well, for this will be a birth and beginning of your destined leadership on Dondromogon." The voice was telling me that I had been snatched from worlds away, for a specified purpose here on whatever windswept planet Dondromogon might be. But because Dondromogon wavers on its axis, there are two lunes of its surface which from time to time shift from night to day. Of course, such areas, between the hot and cold hemispheres, would be buffeted by mighty gales ... the voice was to be heard again: "War is fought between the two strips of habitable ground. War, unceasing, bitter, with no quarter asked, given or expected. Dondromogon was found and settled long ago, by adventurers from afar. "Suffice it that you were needed, and that the time was ripe. There is a proper time, like a proper place, for each thing and each happening. Especially as I don't know who I am, or where I'm from, or anything that has happened longer ago than just a moment. "There's a bigger reward for capture than for warning," objected his friend in turn, "and whoever comes to take this man will claim 'capture.'
 So he can be birthed on a clean slate as the new Dondromogon leader.
 Earth is not something a Dondromogon leader should remember.  So he can be birthed on a clean slate as the new Dondromogon leader.  So that the Dondromogons will be suspicious of him  To better assimilate to Dondromogon culture.