It means 2 related things: 1) Outside armies have a poor track record in winning wars in Asia. History books are full of those failures ... 2) because most As

It means 2 related things: 1) Outside armies have a poor track record in winning wars in Asia. History books are full of those failures ... 2) because most Asian countries have millions of citizens to conscript, on their home turf, and not many centralized targets to bomb, the battle is asymmetrical. Each soldier just needs an AK-47 and directions to the front. In the US-Korean War, China just kept pouring troops over the border until the US was overwhelmed, which illustrates the "millions" part. Same against Japan in WW2. Japanese victories became slower and slower as China mobilized human waves against them. The Japanese military told everyone the entire war would take weeks, but it extended into years. In Afghanistan, the Russians gave up on defined battles and went with genocide (poisoning wells, shooting on sight, etc.)