In #47 The Resistance, the Yeerks discover where the valley of the free Hork-Bajir is, and subsequently invade it. The Yeerks are eventually forced to retreat.
In the following books, the Animorphs, their families and the free Hork-Bajir continue to live in something they refer to as "the valley" or "the valley of the free Hork-Bajir".
- Is this the same valley that the Hork-Bajir used to live in before the Yeerk attack? (The one hidden by the Ellimist.)
Wouldn't the Yeerks have returned to that Valley with reinforcements to wipe out the free Hork-Bajir?
- So if yes to #1, how could it be safe for everybody to live there when the Yeerks knew of its location?