Terracotta wall tiles is a special type of terracotta art form. The clay is first processed and then spread on the floor, maintaining uniform thickness. Then the theme is created on the surface. The whole creation is then cut into pieces to facilitate firing. The pieces are then separately processed. 
The whole process requires dedicated skilled labour and is time consuming. As the tiles are created completely by hand, it becomes very difficult to create a replacement if a piece gets broken ( as it's too difficult to produce a tile of exact same dimension after firing).