Indicates a general belief or widely accepted view; often translated as 'is considered', 'is seen as', 'is said to be'.
The ～とされる grammar point is used to express what is generally believed or widely accepted in a society or group of people. It can also be used to express what is reputed or alleged about something or someone. It translates to 'is considered', 'is seen as', 'is said to be' in English. The formation differs depending on whether it is used with a verb, い-adjective, な-adjective, or noun.