@greatninja3 : while he should research history more, a single extinction is something he could easily miss unless there was something else more significant involved, or people mentioned ing how they compensate for the loss, especially since 1000 years means it is effectively ancient history to everyone else (and before me met Pochi).
Though given the state of affairs (considering they lost a city and did nothing to reclaim the lands), I would laugh if he got that acid within the last millennia, and the people only think the species is extinct, but there is still a population somewhere outside what territory is still inhabited and explored.
@Riger : it is not what he did, but how and why he did it. 😉