The full moon day (Pōya) in June is known in Sinhalese as Poson. This full moon is highly significant for Theravāda Buddhists in Sri Lanka because it commemorates the introduction of Buddhism to Laṅkā by the Arahant Mahinda in 236 BCE during the reign of King Devānampiya Tissa (250–210 BCE). There are fascinating stories associated with the introduction of Buddhism. One of them is that the Arahant Mahinda tested the local ruler by producing an aptitude test as the Mahāvaṃsa (ch. 14: 16–22) recorded to assess his competence in understanding and potential of expounding and spreading the Dhamma. The wise king became a Buddhist ruler. His Queen Anula also later became an ardent devotee and subsequently the first Buddhist nun on the island, paving the ground for establishing female monastic order. Laṅkā became then a land of pious men and women who wished to preserve Buddhism.