Complex sentence: The initial hostility of the Five against Tchaikovsky was mitigated by Tchaikovsky's improved relationships, first with Balakirev and then with Rimsky-Korsakov, the latter of whom substantially embraced the cosmopolitan conservatory-based approach, as distinct from pure Russian nationalism.
Split into simpler sentences: The initial hostility of the Five against Tchaikovsky was mitigated by Tchaikovsky's improved relationships, first with Balakirev and then with Rimsky-Korsakov. The latter substantially embraced the cosmopolitan conservatory-based approach, as distinct from pure Russian nationalism.