A safe square is called a castle

And historian al-Mas’udi considered the game a testament to human free will compared to games of chance. Medieval trade along the Silk Road carried the game to East and Southeast Asia, where many local variants developed. In China, chess pieces were placed at intersections of board squares rather than inside them, as in the native strategy game Go. The reign of Mongol leader Tamerlane saw an 11x10 board with safe squares called citadels.