[ADWD Spoilers] Dorne's true strength

[Michael Herman]

The North is very sparsely populated, and also it's as large as all of the other six kingdoms combined so even if they did boast a similar population it would take that much longer for them to gather.

50K might be an exaggeration, but it's not difficult to imagine how Dorne can muster more men than the North.

I could not disagree more, Dorne is desert, it's made fairly clear that much of the inland is pretty much completely inhospitable, the majority of the population is probably focused around the mountains, major rivers and the coast, with most of the inland having an extremely low population density. The north does have a lot of forest and mountains, which are very populous, but even if you ignore that what is left, mostly fairly arable land, though a bit too cold for maximum fertility, the north is still twice as large as Dorne, plus it has a major city and at least one major town.

Torrhen Stark had 30,000 men in the war of conquest, Dorne (to my knowledge) has never fielded more than 10,000. Certainly the Dornish can reach full strength before the north, but there is no way they could have a total greater military strength.

[Lord of Moat Cailin]

Kevan's remark is also a reflection of how devastated the Lannisters were by the war of five kings. They fought the North and Riverlands, and suffered devastating casualties, whereas their win by assassination leaves a fair amount of northern/riverland strength intact. The Vale stayed out of it, and likely will continue to do so. The Lannisters also clashed with the Stormlands, which also took a bit of a beating. Net result: Lannisters decimated, North/Riverlands leaderless, Vale intact (but not one of the most populous to begin with), Dorne intact, Stormlands battered, Reach fighting on two fronts.

The red wedding wasn't just an assasination, they also massacred the tully ad stark army, plus there was the Green Fork and the Sack of Winterfell so between those things the armies of the North and Riverlands are mostly desimated