Dembiya ( Ge'ez ደምቢያ dembīyā; also transliterated Dembea, Dambya, Dembya, Dambiya, etc.) is a historic region of Ethiopia, intimately linked with Lake Tana. According to the account of Manuel de Almeida, Dembiya was "bounded on East by Begemder, on South by Gojjam, on West by Agaws of Achefer and Tangha. Lake Tsana, formerly called Dambaya, is in this region." Alexander Murray, in his preface to the third volume of Bruce's account, further describes it as "on the east it includes Foggora, Dara, and Alata; on the north-east Gondar, the metropolis, and the rich district beneath it; on the southwest, the district of Bed (the plain barren country) and, on the west, the lands around Waindaga and Dingleber."
Dembiya was incorporated into the Begemder province (which previously only included lands to the east of Lake Tana) during the reign of Emperor Haile Selassie, and in 1996 became a woreda of the Amhara Region.
Dembiya is one of the woredas in the Amhara Region of Ethiopia. It is named for the former province of Dembiya, which was located roughly in the same location. Part of the Semien Gondar Zone, Dembiya is bordered on the south by Lake Tana, on the southwest by Takusa, on the west by Chilga, on the north by Lay Armachiho, and on the east by Gondar Zuria. Towns in Dembiya include Aymiba, Chuahit, Gorgora and Koladiba.
Rivers within this woreda include the Lesser Angereb and Derma, which flow south into Lake Tana, and the Atbarah. A survey of the land in this woreda shows that 64% is arable or cultivable and another 25% under irrigation, 6% pasture, 4% forest or shrubland, and the remaining 1% is considered degraded or other. 287 square kilometers adjacent to Lake Tana is subject to regular and extensive flooding.