King's Indian: Petrosian, Stein, 8.Bg5

King's Indian Defense

Definition

The King’s Indian Defense (KID) is a hyper-modern opening for Black that arises after the moves 1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6. Instead of immediately occupying the center with pawns, Black allows White to build a broad pawn center and then seeks to undermine it later with pawn breaks such as …e5 or …c5.

Typical Move-Order

1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Nf3 O-O 6. Be2 e5 (main line) From this tabiya dozens of distinct systems branch out, including the Petrosian, Classical, Sämisch, Fianchetto, and Four Pawns Attack.

Strategic Ideas

Black attacks the dark-squared center (d4, e4) with pawn breaks …e5, …c5.
Typical kingside assault: …f5, …g5, …f4, and a rook lift via …Rf6-g6/h6.
White decides whether to maintain the center (as in the Petrosian System) or open it quickly (e.g., the Sämisch with f3 and g4).
The resulting positions are among the richest and most double-edged in chess strategy.

Historical Significance

Popularized in the 1920s by Indian masters Moheschunder Bannerjee and later by Teichmann, then refined by Soviet greats such as Bronstein, Geller, and Boleslavsky. Bobby Fischer used the KID as a main weapon on his road to the 1972 World Championship, and Garry Kasparov revived it in the 1980s against Karpov.

Illustrative Example

Kasparov – Karpov, World Championship (Game 16), 1985 Kasparov’s thematic …f5 break led to a famous sacrificial attack, cementing the KID’s reputation as one of Black’s most combative replies to 1.d4.

Interesting Facts

The opening has its own nicknames: “King’s Indian Complex” (Botvinnik) and “a perfect reply to 1.d4—provided you like to live dangerously” (Najdorf).
Many engines at top depth now consider the KID objectively risky, yet it remains popular in practical play for its winning chances.

Petrosian System in the King's Indian

Definition

The Petrosian System, named after 9^th World Champion Tigran Petrosian, is reached after 1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Nf3 O-O 6. Be2 e5 7. d5. By closing the center with 7.d5, White blunts the g7-bishop and aims for a slow positional bind rather than an immediate tactical melee.

Strategic Themes

Space Advantage: The pawn on d5 grants White queenside space where play often revolves around c5, b4, and a4.
Prophylaxis: Petrosian’s hallmark—preventing Black’s activity before it starts. The knight jump …Nh5-f4 and the break …f5 are both harder to achieve.
Minor-Piece Manoeuvres: Knights often head to d2-c4 or e1-d3; Black’s knight eyes c5 or h5-f4.

Historical Background

Tigran Petrosian unveiled the system in the late 1950s and early 1960s, using it to neutralize aggressive King’s Indian specialists such as Geller and Boleslavsky. His approach proved so successful that the variation bears his name.

Key Game

Petrosian – Geller, Moscow 1966 Petrosian gradually expanded on the queenside, forced structural weaknesses, and converted a textbook positional advantage—an instructive model for students.

Interesting Facts

Petrosian’s overall score with the system was phenomenal: +13 =29 -2 against elite KID exponents.
The line enjoyed a renaissance when Vladimir Kramnik adopted it in the early 2000s to combat Kasparov’s feared KID.

Stein Variation (8. Bg5) in the Petrosian System

Definition

The Stein Variation is a sharp offshoot of the Petrosian System that appears after 1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Nf3 O-O 6. Be2 e5 7. d5 a5 8. Bg5. Named after Ukrainian GM Leonid Stein, White pins the f6-knight, preparing queenside expansion with Nd2 and a later c5 or b4, while simultaneously discouraging Black’s …Ne8 and …f5 plan.

Strategic Aims

Pin & Pressure: 8.Bg5 fixes the knight on f6, indirectly restricting Black’s typical kingside pawn storm.
Queenside Play: White follows with Nd2, a3, Rb1, b4, and c5, exploiting the space gained by 7.d5 and 7…a5.
Dark-Square Control: By weakening Black’s grip on e5 and g5, White hopes to reroute pieces to e4 and c4.

Typical Continuations

8…h6 9.Bh4 Na6 10.Nd2 Qe8 11.a3 Bd7 12.b3, an elastic structure where Black must decide between …Kh7 and a central break.
8…Na6 9.Nd2 Qe8 10.g4!?, a double-edged line tested by modern engines.

Historical Context

Leonid Stein introduced the move 8.Bg5 in the mid-1960s, scoring several brilliant wins. The line was later analyzed by Hungarian GM Lajos Portisch and became a specialty of Anatoly Karpov during his junior years.

Illustrative Game

Stein – Geller, USSR Championship 1967 After 8.Bg5, Stein’s relentless queenside push with a3, Rb1, and b4 overwhelmed Geller’s defenses, showcasing the variation’s positional venom.
(Full score truncated for brevity.)

Interesting Tidbits

ECO Code: E92.
Modern practitioners include Ding Liren and Levon Aronian, who employ 8.Bg5 as a low-theory surprise weapon.
In engines’ top lines, 8.Bg5 sometimes transposes into Benoni-style structures after …h6 Bh4 g5 Bg3 Nh5.