Learn Farsi: این ممنوعیت سال گذشته وضع شده بود. - This prohibition had been enacted last year.

Mamnu' is an adjective meaning 'forbidden' or 'prohibited.' By adding the Arabic-derived suffix -iyat, it turns into an abstract noun, mamnu'iyat, meaning 'prohibition' or 'ban.' You will see this suffix often in formal and legal Farsi (for example, mas'uliyat for 'responsibility').

Why is the verb vaz' shode bud instead of just vaz' shod?

Vaz' shode bud is the past perfect passive, meaning 'had been enacted.' It emphasizes that the ban was put into place at a point in the past before another past event or before the timeframe currently being discussed. If it were vaz' shod, it would simply be the simple past passive ('was enacted').

What does vaz' mean here, and what verbs are usually paired with it?

Vaz' refers to 'laying down' or 'establishing.' It is a highly formal word used almost exclusively in official or legal contexts, such as vaz'-e qânun (enacting a law). To say 'to enact' or 'to impose,' you use the compound verb vaz' kardan (active) or vaz' shodan (passive, as seen here).

Is there an Ezafe used in sâl گذشته?

Yes, it is pronounced sâl-e gozashte. Gozashte acts as an adjective here (meaning 'past' or 'previous') modifying sâl (year), so the Ezafe is required to link the noun to its modifier.