The area vaguely resembles an isoceles triangle with its base running northwest to southeast and its apex northeast of the base's center. At the northwest angle is Lake Chad(3)--about half of which is within the nation it shares a name with. The Chari River empties into the lake and its lower course forms much of the triangle's base. The land is low lying scrub and grassland where it's not farmed.
Almost two million people live in the two prefectures. The majority--probably almost two thirds--speak Shuwa(4) Arabic as a first language, and more as a second language. About one in twenty speak Buduma; perhaps three times that use Hausa; about one in fifteen speak Bagirmi; and numerous other languages comprise the rest.
The area is near the national religious divide between the purely Moslem north and the more diverse south. Probably this area is mostly Moslem with some indiginous religions.
Njamena, the capital, has 1.3 million metropolitan residents; about three-fourths of a million in the city proper. No other city comes close. It sits where the Logone River joins the Chari, on the Cameroon(5) border just north of the center of the triangle's base.
Arab traders arrived in the seventh century introducing the classical Arabic which eventually gave rise to Shuwa Arabic. The older form still has no first language speakers but remains an official language.
Otherwise there are three lingusitic groups represented. I. the Fulani--speakers of Fulfulde--arrived sometime in the last 500 years, perhaps in the 19th century. II. Bagirmi was used by a 16th century empire and is still spoken. It is one of the Nilo-Saharan languages. These--according to one theory(6)--are all dervied from the physical 'acquatic tradition' of northern Africa, about 10,000 years ago. III. Several languages are Chadic. Thousands of years ago(7) these spread westward across Africa.
The French conquest has left only a patina. Despite its official status it is rarely a first language and takes a distant second to Shuwa Arabic as a second language.
northwest
north
east of Chari-Baguirmi
southeast and south
west of the Lagone and Chari Rivers
southwest of the lake
(1) Lac in French.
(2) Tchad in French.
(3) Africa's third largest lake before it started to dry up.
(4) Also called Chadian.
(5) Cameroun in French.
(6) That of J.E.G. Sutton and Patrick Munson.
(7) 18,000 years ago the group's predecessor, Proto-Afroasiatic, was said to have been spoken far to the east.