hereditary; handed down from ancestors
A yojijukugo used for things passed down through generations, such as property, traditions, or traits.
This land has been handed down from our ancestors.
先祖代々 is more common and means 'for generations' or 'ancestral', often used adverbially. 祖先伝来 is more formal and emphasizes the act of transmission from ancestors.
A yojijukugo composed of 祖先 (ancestor) and 伝来 (transmission). The exact historical derivation is uncertain, but the meaning is transparent from its components.