源于 is a prepositional phrase meaning 'originate from' or 'stem from'. It combines the noun 源 (yuán), meaning 'source' or 'origin', with the preposition 于 (yú), which marks location, time, or cause — here indicating where something begins. Together, they form a formal yet common expression used to explain roots, causes, or historical beginnings of phenomena, traditions, ideas, or physical features.

This phrase appears frequently in written Chinese — in academic texts, news reports, historical descriptions, and cultural explanations — but is less common in casual speech, where simpler alternatives like 来自 or 出自 are preferred. It emphasizes causality or derivation rather than mere location, so it’s often used when discussing origins of customs, languages, species, or geographical features. The structure is typically [Subject] + 源于 + [Source/Cause], and it always precedes a noun or noun phrase, never a verb.