The Haya (or Bahaya) are a Bantu ethnic group based in Kagera Region, northwestern Tanzania, on the western side of Lake Victoria. With over one million people, it is estimated the Haya make up approximately 4% of the population of Tanzania. Historically, the Haya have had a complex kingship-based political system. Agriculture, particularly banana farming, is central to Haya economic life. They are credited with the independent development of carbon steel dating to 2000 years ago using pre-heating techniques. According to Hans Cory, the term Bahaya (Haya for fisher-people) was originally used to differentiate the Haya from the Banyambo of Karagwe. This distinction is said to be based on cultural differences, with the Haya economy predominantly oriented toward fishing and other industries on Lake Victoria and the Banyambo predominately engaged in pastoralism. Other sources on the origin of the term Haya cite oral accounts that state it derives from a goddess named Muhaya, whose father was King Ruhinda Mushure. This second version is not as popular. Linguistic evidence indicates the Haya settled in the Kagera Region during the time of the Bantu expansion. They are believed to be some of the earliest inhabitants in the region to practice iron smelting and were part of the iron-making Urewe pottery culture (ancestral to many Eastern Bantu groups) dating from the 5th century BC to the 6th century AD. Around 200 BC is when the first strong evidence of Early Iron Age settlements were established along Lake Victoria in Buhaya. Iron tools may have helped expand agricultural production in the region which included a combination of cereal crop cultivation (finger millet and sorghum), root-cropping, and the gradual use of beans. Between 800 and 1500 AD, Bahaya lifeways were greatly influenced by other Bantu peoples moving in from an area further north in the African Great Lakes region. These northern Bantu peoples, whose descendants founded the kingdoms of Bunyoro-Kitara and Buganda, are said to have brought with them new breeds of cattle as well as varieties of banana.