This is the 16896th most frequent Russian word.
содержались
"Were contained" or "were maintained."
Here, 'содержались' signifies that the document included or held the important details within it.
В документе содержались важные сведения.
The document contained important information.
In this sentence, 'содержались' denotes that these facts were encompassed or presented within the book.
В книге содержались интересные факты о природе.
The book contained interesting facts about nature.
In this usage, 'содержались' implies that the animals were accommodated or kept in the building.