Actually, the reason was quite simple. Drawing on his previous experience with the Five-Tails, Li Fusheng had made a few adjustments to the Dragon Vein seal.
He had masked the aura of leaking Dragon Vein energy. This would prevent anyone from sensing the boundless natural energy the moment they got close.
However, since it wasn't a complete seal, the land around Loulan still retained a fair amount of natural energy, making the concentration much higher than elsewhere.
Chapter 139