as-Suli's Diamond

From Wikipedia (English):
The problem called "as-Suli's Diamond" went unsolved for over a thousand years. In shatranj, the "queen" (counsellor) is a very weak piece, able to move only a single square diagonally. It is also possible to win in shatranj by capturing all pieces except the king.

as-Suli commented:

“This ancient position is so difficult that there is no one in the world who would be able to solve it, except those I have taught to do so. I doubt whether anyone did this before me. This was said by al-Suli.”
David Hooper and Ken Whyld studied this problem in the mid-1980s but were unable to crack it. It was finally solved by Russian Grandmaster Yuri Averbakh.
as-Suli gave the first move of the solution (1.Kb4) which was the same as Averbakh's solution; Averbakh was impressed with the obvious prowess of the Arab master.

Solution (from the German Wikipedia) is in the comments. You have 1000 years, starting NOW...




Juri Awerbach stated the following main line in the 1980s: 1. Kb4 Kd6 2. Kc4 Ke6 3. Kd4 Kf6 4. Kd5 Kf7 5. Ke5 Kg7 6. Ke6 Kg8 7. Kf6 Kh8 8. Kg6 Kg8 9. Fd2 !! Kf8 If the black Fers tries to escape the corner with 9.… Fb2, it only gets closer to the white king. 10. Fc1 Ke7 11. Kf5, and the king will capture the black Fers and win. Computer help later found a more stubborn defense that Awerbach suspected as-Suli knew too. 6.… Kf8 7. Kd6 Ke8 8. Kc6 Kd8 9. Kb6 Kc8 10. Kc5 Kd7 11. Kb5 Kc7 12. Kc4 Kd6 13. Kb4 Ke5 14. Ka3 Kd5 15. Kb3. The starting position is reached with black to move. It is a forced variation. With the previous extended triangulation manoeuvre, White has given the obligation to move to Black. Black loses after 15.… Kc5 because White now successfully transfers the Fers to c1 and the king to b1. Another possibility is 15.… Ke4 16. Ka2 Kd3 17. Fb4 Kc4 18. Fa3, and White wins, because the black king can no longer attack the white Fers and the black piece falls on a1.
(translation from German Wikipedia by Google and me)