Ali Gazi was a ruler of the Bornu Empire

Bornu Empire

The Bornu Empire was an African state of Nigeria from 1396 to 1893. It was a continuation of the great Kanem Empire founded centuries earlier by the Sayfawa Dynasty...

. Prior to his reign, the Sefuwa ruling house had split into two ruling branches. The result was palace intrigues and internal strife. He consolidated his reign by killing the candidate from a rival house and restricting opposition from challengers.

Ali Gazi later took on the Bulala nomads, who had driven out his people from Kanem

Kanem Region

Kanem is one of the 22 regions of Chad, corresponding to the former prefecture of Kanem. Its capital is Mao. It is named after the famous Kanem Empire, which was centered in this vicinity.The region of Kanem is divided into 3 departments:-Demography:...

 during the decline of the Kanem Empire

Kanem Empire

The Kanem Empire was located in the present countries of Chad, Nigeria and Libya. At its height it encompassed an area covering not only much of Chad, but also parts of southern Libya , eastern Niger and north-eastern Nigeria...

. He defeated them and re-captured the old Kanem capital, Njimi

Njimi

Njimi was the capital of the Kanuri state of Kanem , north of Lake Chad, from the eleventh through the fourteenth centuries. Founded by the Sefawa dynasty in the eleventh century, the town dominated trans-Saharan trade in ivory and slaves between the central Sahara and Libya. The precise location...

. He also founded a new capital at Birni Gazargamu.