Bornu, or Bornoro, a powerful but declining state of Central Africa, somewhat larger in extent than England, bounded on the E. by Lake Chad, and N. by the Sahara. By treaty with France of 1890 it is within the British sphere of influence. The greater part of the country is perfectly level, and much of it is liable to be overflowed in the rainy season, which lasts from October to April. The heat from March to June is excessive, ranging from 104° to 107° F. The two principal rivers are the Shari and the Komaduga Yaobe, both of which fall into Lake Chad. The soil is fertile, yielding plentiful crops of maize, millet, and other tropical produce. Wild beasts are very numerous. The population, which is estimated at about five millions, is mostly of negro race, and called Bornuese or Kanuri. The ruling race, called Shuwas, are of Arab descent and bigoted Mohammedans; but many traces of fetichism remain among the masses. Whatever they have of civilisation is derived from the Arabs. The slave-trade is eagerly prosecuted in Bornu. In the beginning of the 19th century, Bornu was conquered by the Fellatahs, whose yoke, however, was soon shaken off. Dr Nachtigal, who visited Bornu in 1870, described it as rapidly decaying. The ruins of Birni, the old capital, on the Yaobe, may still be seen. Kuka or Kukawa, the present capital, on the west shore of Lake Chad, has a pop. of about 60,000. Gornu, to the south-east, is still more populous, and has one of the most important markets of Central Africa.