1. Geography
Southeast Asia consists of the mainland and islands. On the Mainland, there will be three important mountains: Arakan mountain hills, Tenasserim hills Range and and Annamite range. Three of them the source of the river Such as the Irrawaddy River, Salween River, Chao Phraya River And Red River. On the islands, there will be many straits, such as Lombok Strait, Sunda strait and Malacca strait. All is the main route of navigation.