The Level 80 map, Black Rock Mountain was a fairly important map on Invincible Continent. It was not to say that this was the best place to level up but rather, this was the place for great equipment drops.
The most powerful level 80-90 Epic-level equipment were from this map.
Black Rock Mountain was surrounded with Black Squamous Whelps, Elite Draconians and even Chief-level Black Squamous Drakes with their own names. Their ATKs could be really powerful that even players of the same level would not be able to withstand a single breath.
Both whelps and drakes were Ancient-level creatures. Hence, they were naturally stronger than regular monsters. Relatively speaking, killing them would land players high EXP.
The entire coal-black mountain peak emitted black smoke all year round. This was because it was situated above a mountain range of volcanoes. Black Dragon King Ferrian's lair was situated under this volcanic mountain range.