"Ms. Elenora, how is it? This tunnel goes straight through the mountain area to the other side of the mountain range. You wouldn't have to think about the snow to block your way or about any wandering spirit beast." –Henry said.
"Why is there something so bizarre here?" –Elena asked.
"I don't really know. But there are a lot such tunnels around the ridge mountain. And each of them lead to some different place. Maybe this was routs created thousands of years in the past in order to transport goods. These rocks are very old after all." –Henry said. It was something that puzzled him once too. But after he didn't find any records about it he just gave up and didn't care.
He is a merchant. Not some alchemist or adventurer. Knowing the origins of this isn't his concern.
He takes the world as it is. Changing it isn't his goal.