I currently live in Taiwan, and we are currently experiencing "ghost month". The Wikipedia article for Ghost Festival starts with:
The Ghost Festival, also known as the Hungry Ghost Festival, Zhongyuan Festival or Yulan Festival (traditional Chinese: 盂蘭節) is a traditional Buddhist and Taoist festival held in Asian countries.
The use of "traditional festival" suggests it may be more of a cultural tradition than a strict Buddhist concept.
Does the idea that hungry ghosts or spirits escape from (some subset of) Hell once a year and need to be fed have any root in the early origins of Buddhism, or is this an add-on concept coming from cultural ideas or perhaps from Taoism?