Communist bloc
Refers to the group of countries under communist rule, especially during the Cold War era.
During the Cold War, the Communist bloc was united around the Soviet Union.
共産圏 is a more common term for 'communist bloc' or 'communist sphere'. 共産国家郡 is a less frequent, more formal compound.
Compound of 共産 (communist) + 国家 (nation) + 郡 (group, bloc). The exact historical derivation is uncertain; it appears to be a direct translation of 'Communist bloc'.