Home of the Dragyns

Humanoids realize their cities have been overrun with intelligent and aggressive dragyns. They avoid the cities and, in fact, avoid making cities altogether for many years.
  In their scouting and attempts at resettling of the now empty cities, humanoids discover that their territories have become overrun with numerous hostile dragyns of all shapes and sizes.
  The dragyns are strangely intelligent and hunt any humanoids entering the cities with extreme prejudice.
  Since cities and their surrounding areas were almost exclusively struck by the Unseen Inferno, many humanoids develop a superstition; too dense of a populace invites trouble and disaster.