800 years old Arabic chess treatise opening

In this eight centuries old chess treatise (1257 AD, 655 H), opening truly meant opening: each player could place the pieces to his/her convenience before first move (from page 32):

Kitāb fī al-shaṭranj wa-manṣūbātihi wa-mulaḥih كتاب في الشطرنج ومنصوباته وملحه [12r] (32/276)