Complex sentence: Kavur then served as ambassador in Sofia, Bulgaria, followed by five years in Moscow--a challenging ambassadorial posting, under Nikita Krushchev at the height of the Cold War (1955--60).
Split into simpler sentences: Kavur then served as ambassador in Sofia, Bulgaria. This was followed by five years in Moscow-a most challenging ambassadorial posting, under Nikita Krushchev at the height of the Cold War (1955--60).