What is the origin of Nian beast?

The prototype of "Nian Beast" comes from Mandrill or Shan Gui in ancient literature, and this beast, which was expelled as a monster, should be a primate ape living in the deep mountains. The folk custom of setting off firecrackers on Spring Festival couplets should also be aimed at expelling this ape. There is no record of Nian beast in ancient books. The earliest document describing Nian beast comes from modern times, and it is the story "The Story of Nian" published by 1959 in Xinmin Evening News. It can be seen that Nian beast should be a modern folk interpretation, not a traditional fairy tale.