r1bnkb2/1p1p3r/pB1p2p1/1q5p/2P1PpPP/1P5B/P2PP3/RN1K2NR b q - 1 21
FEN state: r1bnkb2/1p1p3r/pB1p2p1/1q5p/2P1PpPP/1P5B/P2PP3/RN1K2NR b q - 1 21 ; Best move: b5b6
The current state of the chess board is: Black rook at a8, black bishop at c8, black knight at d8, black king at e8 and black bishop at f8. Black pawn at b7, black pawn at d7 and black rook at h7. Black pawn at a6, white bishop at b6, black pawn at d6 and black pawn at g6. Black queen at b5 and black pawn at h5. White pawn at c4, white pawn at e4, black pawn at f4, white pawn at g4 and white pawn at h4. White pawn at b3 and white bishop at h3. White pawn at a2, white pawn at d2 and white pawn at e2. White rook at a1, white knight at b1, white king at d1, white knight at g1 and white rook at h1. Black queenside is the only castle move available. Half move number is 1. Full move number is 21. Black to move.