The dark home was the place where the Listeners resided when they were the Last Legion.
Eshonai asks her mother why they left the dark home and her mother responds as follows:
"Ah, now that's an old song, Eshonai," Mother said. "A dark song, not for a child like you."
"Long are the days since we knew the dark home," Mother sang softly ... . "The Last Legion, that was our name then. Warriors who had been set to fight in the farthest plains, this place that had once been a nation and was now rubble. Dead was the freedom of most people. The forms, unknown, were forced upon us. Forms of power, yes, but also forms of obedience. The gods commanded, and we did obey, always. Always.