They're extremely intelligent. Highly evolved. And they don't like sharing the planet.

Reign of Fire

In post-apocalyptic England, an American volunteer and a British survivor team up to fight off a brood of fire-breathing dragons seeking to return to global dominance after centuries of rest underground. The Brit -- leading a clan of survivors to hunt down the King of the Dragons -- has much at stake: His mother was killed by a dragon, but his love is still alive.