This is the 5325th most frequent Russian word.
основаны
"Основаны" means "are based (on)."
The word 'основаны' here is the plural past participle form of the verb 'основывать', denoting that the conclusions derive their foundation from scientific research.
Наши выводы основаны на научных исследованиях.
Our conclusions are based on scientific research.
In this sentence, 'основаны' refers to the basis or inspiration for the content of the books, showing their derivation from actual historical occurrences.
Эти книги основаны на реальных событиях.
These books are based on real events.
The use of 'основан' here conveys that the project's establishment or initiation heavily relied on the backing provided by the community.