Teleportation Circle Technique Vs Space Locking Technique
The distance between his place and that cave wasn't that far, as he reached it in one hour's flight. Throughout the way, he found some warriors moving out from the direction of that cave.
The moment he saw that cave, he felt the energy concentration there, it was really monstrous. He didn't need to go inside to confirm his guess, as he felt huge energy fluctuations, like some sort of huge technique was activated and then deactivated.
That linked with all the constant stream of warriors coming from inside the cave made him realize there was a teleportation circle of a similar technique inside the cave.
This technique was considered common back in his days, as sects usually were built on a huge stretch of land, and they always ruled over a large piece of forests and controlled many ore mines.