In this variation, Black fianchettoes a Bishop on the h8-a1 diagonal. The name "Dragon" comes from the resemblance of Black's kingside pawn structure to the constellation Draco. The Dragon Variation is one of the sharpest variations of the Sicilian Defence, making it one of the sharpest of all chess openings.
Considered to be the main line that gives maximum chances for both sides is the Yugoslav Attack (also known as the Rauzer Attack for its inventor) which continues 6.Be3 Bg7 7.f3. The point of White's last move is to safeguard e4 and to stop Black from playing ...Nf6-g4 harassing White's dark squared bishop. Note that Black cannot play 6.Be3 Ng4?? immediately because of 7.Bb5+ winning a piece. Play usually continues 7...0-0 8.Qd2 Nc6 and now there are fundamentally two distinct branches with 9.0-0-0 leading to more positional play while 9.Bc4 leads to highly tactical double-edged positions.
The Yugoslav exemplifies the spirit of the Dragon with race-to-mate pawn storms on opposite sides of the board. White tries to break open the Black kingside and deliver mate down the h-file, while Black seeks counterplay on the queenside with sacrificial attacks. Typical White strategies are exchanging dark-squared bishops by Be3-h6, sacrificing material to open the h-file, and exploiting pressure on the a2-g8 diagonal and the weakness of the d5 square.
Black will typically counterattack on the queenside, using his queenside pawns, rooks, and dark squared bishop. He sometimes plays h5 (the Soltis Variation) to defend against White's kingside attack. Other typical themes for Black are exchanging White's light-square Bishop by Nc6-e5-c4, pressure on the c-file, sacrificing the exchange on c3, advancing the b-pawn and pressure on the long diagonal. Black will generally omit ...a6, because White will generally win a straight pawn attack, because black has given White a hook on g6 to attack. Generally, White will avoid moving their pawns on a2/b2/c2, and so Black's pawn storm will nearly always be slower than White's respective one on the kingside. Black can frequently obtain an acceptable endgame even after sacrificing the exchange because of White's h-pawn sacrifice and doubled pawns.
After years of believing White's best play and chance for advantage lay in the main line with 9.Bc4, this older main line made a major comeback. White omits Bc4 in order to speed up the attack. It used to be thought that allowing 9... d5!? here allows Black to equalize easily but further analysis and play have proved that things are not so clear cut. In fact, recently Black experienced a time of difficulty in the 9... d5 line facing a brilliant idea by Ivanchuck which seemed to give White the advantage. In fact some Black players began experimenting with 9... Bd7 and 9... Nxd4. Fortunately for Black, the 9... d5 line has been doing better in practice. A brilliancy found for White one day is soon enough overturned by some new resource for Black. A case in point is the following line where the evaluation of a major line was turned upside down overnight because of an ingenious queen sacrifice played by GM Mikhail Golubev, an expert on the Dragon Variation. After 9.0-0-0 d5!? play continued 10.Kb1!? Nxd4 11.e5! Nf5! 12.exf6 Bxf6 13.Nxd5 Qxd5! 14.Qxd5 Nxe3 15.Qd3 Nxd1 16.Qxd1 Be6!, where Black has sufficient compensation for the queen.
The purpose of 9.Bc4 is to prevent Black from playing the freeing move ...d6-d5. The variations resulting from this move are notorious for having been heavily analysed. In addition to covering d5, White's light-squared bishop helps cover White's queenside and controls the a2-g8 diagonal leading to Black's king. However, the bishop is exposed on c4 to an attack by a rook on c8, and usually has to retreat to b3, giving Black more time to organize his attack. Common in this line is an exchange sacrifice on c3 by Black to break up White's queenside pawns, and sacrifices to open up the long diagonal for Black's bishop on g7 are also common. An example of both ideas is the line 9.Bc4 Bd7 10.0-0-0 Rc8 11.Bb3 Ne5 12.h4 Nc4 13.Bxc4 Rxc4 14.h5 Nxh5 15.g4 Nf6 16.Bh6 Nxe4! 17.Qe3 Rxc3!.
The Soltis Variation was the main line of the Dragon up until the late 1990s. Garry Kasparov played the move three times in the 1995 World Championship against Viswanathan Anand, scoring two wins and a draw. The line goes 9.Bc4 Bd7 10.0-0-0 Rc8 11.Bb3 Ne5 12.h4 h5 (the key move, holding up White's kingside pawn advance). Other important deviations for Black are 10...Qa5 and 12...Nc4. More recently, White players have often avoided the Soltis by playing 12.Kb1, which has proven so effective that Black players have in turn tried to dodge this with 11...Rb8, known as the Chinese Dragon.
When Black adopts the Dragon formation without 2... d6, White must watch out for ...d5 which often immediately equalizes. Lines where Black does this include the Accelerated Dragon (1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 g6) and Hyper-Accelerated Dragon (1.e4 c5 2.Nf3 g6).
Some famous exponents of the Dragon are Veselin Topalov, Andrew Soltis, Jonathan Mestel, Chris Ward, Sergei Tiviakov, Alexei Fedorov, the late Tony Miles and Eduard Gufeld. Garry Kasparov used the Dragon with success as a surprise weapon against world title challenger Viswanathan Anand in 1995 but did not use it subsequently. The Dragon saw its popularity declining in the late 1990s as a result of White resuscitating the old line with 9.0-0-0, however recently there has been a resurgence with moves such as the Chinese Dragon 10.0-0-0 Rb8!? and an injection of fresh ideas in the 9.0-0-0 line by Dragon devotees.