north are similar to those in Thailand, while those in the south are similar to those in Java. New materials, such as glasses and nails, were brought in by Europeans, changing the architecture. Houses are built for tropical conditions, raised on stilts with high roofs and large windows, allowing air to flow through the house and cool it down. Wood has been the main building material for much of Malaysia's history; it is used for everything from the simple kampung to royal palaces. In Negeri Sembilan traditional houses are entirely free of nails. Besides wood, other common materials such as bamboo and leaves were used. The Istana Kenangan in Kuala Kangsar was built in 1926, and it the only Malay palace with bamboo walls. The Oral Asal of East Malaysia live in longhouses and water villages. Longhouses are elevated and on stilts, and can house 20 to 100 families. Water villages are also built on stilts, with houses connected with planks and most transport by boats. Music Traditional Malay music and performing arts appear to have originated in the Kelantan-Pattani region. The music is based around percussion instruments, the most important of which is the gendang (drum). There are at least 14 types of traditional drums. Drums and other traditional percussion instruments are often made from natural materials such as shells. Other instruments include the rebab (a bowed string instrument), the serunai (a double-reed oboe-like instrument), the seruling (flute), and trumpets. Music is traditionally used for storytelling, celebrating life-cycle events, and at annual events such as the harvest. Music was once used as a form of long-distance communication. Traditional orchestra can be divided between two forms, the gamelan which plays melodies using gongs and string instruments, and the nobat which uses wind instruments to create more solemn music. In East Malaysia, ensembles based around gongs such as agung and kulintang are commonly used in ceremonies such as funerals and weddings. These ensembles are also common in the southern Philippines, Kalimantan in Indonesia, and in Brunei. Chinese and Indian Malaysians have their own forms of music, and the indigenous tribes of Peninsula and East Malaysia have unique traditional instruments. In countries such as Singapore, Malaysia and Indonesia it is believed that performing at the house during Hari Raya (a traditional malay festival) is a good belief as it brings goodluck and fortune to the performers and host of the house. Within