Oboonii-Bulangiin-Dugang - Obooto-Hural - Obootuin-Hural - Oboo-Hiid - Obor-Gurbaiin-Hiid - Obor-Hangayin - Obor-Hangayskiy-Aymag - Obor-Hangay-Aymag - Obor-Khangai - Obor-Tsuulgata-Jisa - Obor-Ulaan-Haylan - Obor-Urtaiin-Ortoo - Obotu-Khural - Obo-Khid - Ochirvanyin-Dugang - Ochirvanyyn-Dugang - Ochir-Uaniin-Dugan - Ochir-Wangiin-Dugang - Ochzhiman-Khural - Ochzhimin-Khural - Odhan-Hayrhan - Odhon-Hayrhan-Suma - Odkhan-Khairkhan - Odkhan-Khayrkhan-Somon - Ogiinuur - Ogiy - Ogiynuur - Ogoomor - Ogoomoriin-Bayshin - Ogoomoriin-Bayshing - Ogoomoriin-Hiid - Ogorhon-Hiid - Oigor - Ojimin-Hural - Okomur - Oldahu-Hiid - Oldakhu-Khid - Oldao-Khid - Oldoh - Oldoho-Hiid - Oldzeyte - Oldzeyteyn-Horshoo - Oldzeyte-Bulagiin-Hiid - Oldzeyte-Hural - Oldzeyte-Nogoon-Hiid - Oldzeyte-Suma - Oldzeytu - Oldzey-Abagayn-Jisa - Oldzey-Delgereh - Oldzey-Delgerehe - Oldzey-Delgerehe-Suma - Oldzey-Delgerehu - Oldziit - Oldzit - Oldziyt - Olgii - Olgiy - Ologey - Ologey-Hiid - Olonteyn-Dugang - Olon-Baishin - Olon-Bayshin - Olon-Bayshing - Olon-Bulagiin-Bayshin - Olon-Bulagiin-Bayshing - Olon-Huryee - Olon-Khure - Olon-Shandanii-Jisa - Olon-Shandanoy-Chzhisa - Olon-Shandanyy-Chzhisa - Olon-Turagiin-Dugang - Omnodelger - Omnogovi - Omnogovi-Aymag - Omnogov-Aymag - Omnogow - Omolgon-Baatar - Omono-Delger - Omono-Delger-Suma - Omono-Gobi - Omono-Gobi-Aymag - Omono-Gobi-Suma - Omono-Gobi-Sume - Omono-Gobi-Sumu - Ondorhaan - Ondorhangay - Ondorhushuu - Ondorkhaan - Ondorkhangai - Ondorsant - Ondorshil - Ondorshireet - Ondor-Gegeenii-Hiid - Ondor-Haan - Ondor-Haan-Suma - Ondor-Han - Ondor-Hangay-Suma - Ondor-Hurme - Ondor-Hurme-Suma - Ondor-Maydariin-Hiid - Ondor-Shili - Ondor-Shili-Suma - Ondor-Ulaan-Suma - Ondor-Untsa - Ondor-Untsa-Suma - Ongi - Ongiim-Sume - Ongiin - Ongiin-Hiid - Ongin - Ongi-Suma - Ongi-Sumu - Ongoin-Khid - Ongon - Ongon-Elesu - Ongon-Somon - Ongon-Suma - Ongon-Suma-Elesete - Ongon-Sumu - Ongoyn-Khid - Ongyin-Khid - Ongyyn-Khid - Onjuul - Onjuul-Suma - Onon - Ordogoiin-Dugang - Ordogoin-Dugang - Orgil - Orgon - Orgon-Shirigiin-Huryee - Orgoo - Orhirogiin-Dugang - Orhiroogiin-Dugan - Orhon - Orhontuul - Orhon-Aymag - Orhon-Tuula-Suma - Orkhirogin-Dugang - Orkhon - Orkhontola-Somon - Orkhontuul - Ortoogiin-Dugang - Ortoon-Hangay - Ortoon-Shuteen - Ortoo-Suma - Ortsog-Khural - Otgon - Othan - Othan-Sumu - Otochin-Dugang - Ourga - Ovgodiy - Ovogdiy - Ovoot - Ovorhangay - Ovorhangay-Aymag - Ovorkhangay - Ovt - Owoot - Oworkhangai - Oygon - Oygor -