Haiyama 「牌山」 are the tiles arranged in walls. For short, it can also be referred as yama 「山」, which is the word for "mountain". At the start of the game and every hand, every tile is arranged into walls of 34-tiles double stacked 17-tiles wide. Automatic tables are capable of performing the wall building with a button. In computerized games, players need not any concern regarding wall building, as the task is preprogrammed and done instantly. For instances involving just a tile set, every player is required to build their wall.
After the walls are built to their initial position, a dice roll is used to determine the "wall break" at the start of each hand. After the tiles are dealt, every player begins with thirteen tiles. After the dealer takes the first draw, then the wall has 83 tiles before the dealer makes the first discard to start the hand. After subtracting the dead wall tiles, then there are always 69 tiles available for tile draws.