Where does “stan” come from?

I can't write this etymology summary because the chain provided contains only one item (English Stan) with no origin information, earlier language forms, or meaning details beyond "(unknown)." A proper etymology requires at least the headword's meaning and at least one earlier language stage to trace its origin. To write an accurate one-sentence summary, I would need a chain showing progression like: English stan ← [earlier language] [earlier form] ← [even earlier language] [form], along with attested meanings at each stage.

stan (English): An extremely obsessive fan of a person, group,...