Either inherited from Jurchen (guru-un bo-go), or a direct calque of Chinese 國家 / 国家 (guójiā). Compare also the Classical Mongolian equivalent ᠤᠯᠤᠰᠭᠡᠷ (ulus ger).
ᡤᡠᡵᡠᠨᠪᠣᠣ • (gurun boo)
This noun needs an inflection-table template.