とされている

とされている is a passive-like construction used to report that something is generally believed, claimed, or officially recognized by others. It’s not the speaker’s own opinion; instead, it conveys common or authoritative attribution (what people say, what experts state, or what has become accepted). It’s often used for general statements, formal descriptions, and media or official stances about facts, status, or classifications. Compare with と言われている (spoken by others) and とみなされている (regarded as/reputed as); とされている has a nuance of established judgment or status rather than a casual claim.