How did Russian folk music influence Pyotr Ilyich Tchaikovsky’s compositions?

Although Pyotr Ilyich Tchaikovsky was sometimes criticized by his contemporaries for being insufficiently nationalistic compared to composers like The Five, he was clearly inspired by Russian folk music. Rather than using folk elements as ostentatiously as his nationalist peers, Tchaikovsky drew from these sources in a more subtle, often unconscious manner.1

In the words of composer Igor Stravinsky, Tchaikovsky "drew unconsciously from the true, popular sources of our race". His compositions frequently fused these folk-inspired melodic, harmonic, and rhythmic elements with influences from Western traditions, such as Italian opera and the works of Mozart. This unique synthesis allowed him to maintain a distinct Russian character while simultaneously acting as a "Westernizer" with polished technical skill. His ability to harmonize powerful, folk-inspired themes into formally innovative structures remains a hallmark of his legacy as the first great Russian symphonist.12