The Polonaises Op. posth[umous] include Frédéric Chopin's polonaises that were unpublished during his life.
The composer's first works were composed when he was seven years old; his father Nicolas Chopin published these works on behalf of his son. The Polonaises in G minor and B-flat major are among these posthumous pieces.
KK IIa No. 1: Polonaise in G minor (1817)
KK IVa:
No. 1: Polonaise in B-flat major (1817)
No. 2: Polonaise in A-flat major (1821; dedicated to his teacher Wojciech Żywny)
No. 3: Polonaise in G-sharp minor (1822)
No. 5: Polonaise in B-flat minor "Adieu à Guillaume Kolberg" (1826)
This polonaise quotes the tenor cavatina "Vieni fra queste braccia" from Rossini's opera La gazza ladra, which Chopin and Kolberg had seen together
No. 8: Polonaise in G-flat major (1829).