Sri Lanka's culture also revolves around religion. The Buddhist community of Sri Lanka observe Poya Days, which are also important days of prayers to the Hindus, once per month according to the Lunar calendar. The Hindus and Muslims also observe their own holidays. Sri Lankans are very religious because the history of the island has been involved with religion numerous times. There are many Buddhist temples in Sri Lanka and many mosques, Hindu temples and churches all across the island. The religious preference of an area could be determined by the number of religious institutions in the area. The North and the East of the island has many mosques and Hindu temples because a large Tamil and Muslim population resides in those areas. Many churches could be found along the southern coast line because many living in those areas are Roman Catholic or Christian. The interior of the island is mostly the Buddhist population and there are many Buddhists residing in all parts of the island because they are the largest religious group in Sri Lanka.