The stall owner, who was eavesdropping on the others' conversation, shrank his head back when he heard Kastantos was a kingdom from the Mythical Era and decided not to listen any further. As for the Mythical Era, ordinary people only knew of its existence but nothing of what happened or what it entailed.
Looking at Feng Yuan, who was speaking confidently, the stall owner began to doubt if he was just spouting nonsense. But there was no denying that he was followed by two articulate Spirit Beasts. While the ability to speak human language and strength didn't necessarily correlate, without long-term human contact, it would be absolutely impossible for them to learn human speech.
Given Feng Yuan's apparent age, even if he had been with those two Spirit Beasts since he was very young, it would be impossible for them to have learned human language by now.
