also: ないもうこ
noun
Refers to the Inner Mongolia Autonomous Region of China. Both readings are used, but うちもうこ is more common.
内蒙古は中国の北部に位置する自治区です。
Inner Mongolia is an autonomous region located in northern China.
Refers to Outer Mongolia, now the independent country of Mongolia. 内蒙古 is the southern, Chinese-administered part.
From Chinese 内蒙古 (Nèi Měnggǔ), meaning 'Inner Mongolia'. The Japanese readings are based on the kanji: 内 (uchi/nai) + 蒙古 (Mōko).