Nimzo-Indian Defense: Three Knights Variation, Shocron Gambit
ECO E21
Move order
1. d4 Nf6 2. c4 e6 3. Nf3 Bb4+ 4. Nc3 c5 5. d5 b5
Ideas
ECO E covers Indian defenses and related systems where Black fianchettoes or pressures the center from the flanks. White builds a pawn center and keeps the position more closed than after 1. e4. This entry tracks a longer branch in the opening tree. Use the diagram and SAN list to recognize the tabiya, then try the line against Maia to explore typical plans in practice.