The people were suffering from some sort of epidemic/pandemic and thought the frogs were the source - just a guess.
https://en.wikipedia.org/wiki/Frogs_(film)
Maybe it was a several century ahead of its time dry run for the Ray Milland Sam Elliot 1972 Film “FROGS”.
Cheapo guilty pleasure movie favorite of mine.
One of those it’s so bad it’s fun to watch movies.