 He kept busy during this time by editing Mussorgsky's works and completing Borodin's "Prince Igor" (Mussorgsky died in 1881, Borodin in 1887).Rimsky-Korsakov wrote that he became acquainted with budding music patron Mitrofan Belyayev (M. P. Belaieff) in Moscow in 1882.Belyayev was one of a growing coterie of Russian nouveau-riche industrialists who became patrons of the arts in mid- to late-19th century Russia; their number included railway magnate Savva Mamontov and textile manufacturer Pavel Tretyakov.