WIKIPEDIA:

“ Modest Petrovich Mussorgsky, 1870Modest Petrovich Mussorgsky (; – ) was a Russian composer, one of the group known as "The Five". He was an innovator of Russian music in the romantic period. He strove to achieve a uniquely Russian musical identity, often in deliberate defiance of the established conventions of Western music.
Many of his works were inspired by Russian history, Russian folklore, and other nationalist themes. Such works include the opera Boris Godunov, the orchestral tone poem Night on Bald Mountain, and the piano suite Pictures at an Exhibition.
For many years Mussorgsky's works were mainly known in versions revised or completed by other composers. Many of his most important compositions have recently come into their own in their original forms, and some of the original scores are now also available.

Name
The spelling and pronunciation of the composer's name has been a matter of some controversy.
The family name is derived from a 15th or 16th century ancestor, Roman Vasilyevich Monastïryov, who was mentioned in the Velvet Book, the 16th century genealogy of Russian boyars. Roman Vasilyevich bore the nickname "Musorga", and was the grandfather of the first 'Mussorgsky'. The composer is of the lineage of Ryurik, the legendary founder of the Russian [......] ”

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