Little word history, in Latin the word for fish pond is piscina, from piscis for fish, but in all modern Romance languages piscina (or piscine in Frog) means swimming pool. Just imagine the barbarians flooding into Rome and shitting in the streets and swimming in the fish ponds, and then we get nearly a thousand year dark age? So what will future civilizations think of extinct nations? Nothing, they will be living in the ruins of those nations at a medieval level, ignorant of everything that came before.