text: This country's People's Party waited until their ceremonial monarch's death before declaring a socialist republic in 1924.
full_question: This country's People's Party waited until their ceremonial monarch's death before declaring a socialist republic in 1924. It's not the Soviet Union, but a mausoleum in this country's capital once held the bodies of two of its early leaders. Upon its foundation, this country was the third socialist country to exist. In 1939, this country's military clashed several times with the Kwantung Army near the village of Nomonhan and along the Khalkha River. This country's Prime Minister from 1939 to 1952 oversaw the purge of leaders like Peljindiin Gengen and Anandyn Amar for opposition to Stalinism. That Prime Minister was Khorloogiin Choibalsan, who also purged over thirty thousand Buddhist monks and political opponents. In 1924, this country renamed its capital to a word that means "Red Hero." For ten points, name this now-defunct country, ruled by its People's Revolutionary Party from Ulaanbaatar until its dissolution in 1990.
first_sentence: This country's People's Party waited until their ceremonial monarch's death before declaring a socialist republic in 1924.