Ouaddaï Highlands is an area in east of Chad along the border with Sudan. The Ennedi Plateau and the Ouaddaï highlands in the east of Chad complete the image of a gradually sloping basin, which descends towards Lake Chad. There are also central highlands in the Guera region rising to 1,500 m (4,921 ft).
The Yellow Nile is a former tributary that connected the Ouaddaï highlands of eastern Chad to the Nile River Valley ca. 8000 to ca. 1000 BCE. Its remains are known as the Wadi Howar. The wadi passes through West Darfur near the northern border with Chad and meets up with the Nile near the southern point of the Great Bend.
Ouaddaï Prefecture was one of the 14 prefectures of Chad. Located in the east of the country, Ouaddaï covered an area of 76,240 square kilometers and had a population of 543,900 in 1993. Its capital was Abéché.
The Ouaddai Empire (1635–1912) (Also Wadai Empire) was originally a non-Muslim kingdom, located to the east of Lake Chad in present-day Chad. It emerged in the sixteenth century as an offshoot of the Sultanate of Darfur (in present-day Sudan) to the northeast of the Kingdom of Baguirmi.
- Country studies
- Keding, B (2000). "New data on the Holocene occupation of the Wadi Howar region (Eastern Sahara/Sudan)." Studies in African Archaeology 7, 89–104.