Despite knowing Meracydia was a wasteland, I was always curious as to how much of one and of which kind (was it a glassed state, desert, jungle wasteland etc.)... but also how the Miqo'te dwelled in this wasteland before the Age of Endless Frost in the 5th Umbral Era (?) and were they a contributor to the further decline via harvest, hunting, building and so on thus furthering need to migrate.
If stuff lives there though, then it isn't inhospitable and despite knowing that Allag likely blew most of it to waste - I highly doubt they would have subjugated it without building there and forming some colony.