Complex sentence: He was to wait until he entered his sixth decade until the regime enabled him to publish his own work, despite the fact that Anna Akhmatova and Joseph Brodsky, the Nobel laureate amongst others in his immediate circle acknowledged the greatness of his poems.
Split into simpler sentences: He was to wait until he entered his sixth decade until the regime enabled him to publish his own work. Again but despite that Anna Akhmatova and Joseph Brodsky, the Nobel laureate amongst others in his immediate circle acknowledged the greatness of his poems.