Simplify the following text for a Grade 10 native English-speaking person.
Original: According to the Roman tradition , the oldest collection of Sibylline books appears to have been made about the time of Solon and Cyrus at Gergis on Mount Ida in the Troad ; it was attributed to the Hellespontine Sibyl and was preserved in the temple of Apollo at Gergis .
Simplified: They were kept in the Temple of Apollo at Gergis on Mount Ida ( near Troy in Asia Minor ) in the 7th century BC , and said to be written by the Hellespontine Sibyl .