Laṅkāvatāra Sūtra
During the Tang Dynasty, the Zen school's central text shifted to the "Diamond Sūtra" ("Vajracchedikā Prajñāpāramitā Sūtra"). Thereafter, the essential texts of the Zen school were often considered to be the "Laṅkāvatāra Sūtra" and the "Diamond Sūtra".