Reasons

"I had previously said that the number of human tribes had exceeded two hundred near the beginning of the Energy Cultivation Era, after which the number dropped to about sixty after the discovery of the Blue Flame Secondary Law due to our acquisition of more grounds and the merger between the tripes, but after the alliance of the Seven Tree Fathers… Sigh~ the number of human tribes that we know of is 15 tribes, and those tribes control 5% of the world's land mass." Fugon nodded several times in a bad mood, "We 15 tribes have not seen each other for tens of thousands of years and maybe more, For example, we of the Northern Fury tribe, can communicate with two other tribes using war bees, and they can communicate with us using a similar one, and those two tribes can communicate with a fourth tribe, and so on~ This is how we know that we are currently 15 tribes… As for the 16th tribe, it was destroyed just a few years ago."