Dragons were large flying winged creatures with the ability to breathe fire. They roamed the galaxy like moths to a flame, feeding on solar power generated by a sun. Occasionally they could be drawn off course and found their way to Earth several times, becoming creatures of myth and legend.
In the 2010s, a large amount of dragons came to Earth when they were attracted to its sun. They gathered in London and attracted the attention of the military, who dispatched planes to take them out. The Eleventh Doctor and Clara Oswald were in London at the time and decided to save the dragons by guiding them off of Earth. The Doctor flew his TARDIS at a speed which made it resemble a sun and the dragons followed it onto an asteroid. On the asteroid, the dragons were able to feed on the sun's rays far from danger. (COMIC: Dragon Attack)