Daily Chinese Idiom Guessing Game
A long history or tradition that has endured over time, often used to describe cultural heritage or friendship.
源头很远，水流很长。比喻历史悠久。
唐·白居易《海州刺史裴君夫人李氏墓志铭》夫源远者流长，根深者枝茂。”
The friendship between our two countries has a long history.