Bagan (Polish) comes from Burmese ပုဂံ, from Old Burmese ပုကမ်, from Pali gāma, from Sanskrit ग्राम, from Proto-Indo-Aryan grā́mas, from Proto-Indo-Iranian grā́mas, from Proto-Indo-European h₂ger- — to gather; flock, herd.
Ancestry of “Bagan”, step by step
Bagan traces back through 3 separate lines of ancestry.