Climate
Each year a tropical weather system known as the inter-tropical front crosses Chad from south to north, bringing a wet season that lasts from May to October in the south, and from June to September in the Sahel.
Landscape
Broad, arid plains in center, desert in north, mountains in northwest, lowlands in south. Lowest point: Djourab Depression 160 m/525 ft. Highest point: Emi Koussi 3,415 m/11,204 ft.
The dominant physical structure is a wide basin bounded to the north, east and south by mountain ranges such as the Ennedi Plateau in the north-east. Lake Chad, after which the country is named, is the remains of an immense lake that occupied 330,000 km2 205,000 mi2 of the Chadian Basin 7,000 years ago. Although in the 21st century it covers only 17,806 km2 11,064 mi2, and its surface area is subject to heavy seasonal fluctuations, the lake is Africa's second largest wetland.
History
For more than 2000 years, the Chadian Basin has been inhabited by agricultural and sedentary peoples. The region became a crossroads of civilizations. The earliest of these were the legendary Sao, known from artifacts and oral histories. The Sao fell to the Kanem Empire, the first and longest-lasting of the empires that developed in Chad's Sahelian strip by the end of the 1st millennium AD. The power of Kanem and its successors was based on control of the trans-Saharan trade routes that passed through the region.
French colonial expansion led to the creation of the Territoire Militaire des Pays et Protectorats du Tchad in 1900. By 1920, France had secured full control of the colony and incorporated it as part of French Equatorial Africa. The French primarily viewed the colony as an unimportant source of untrained labour and raw cotton. The colonial administration in Chad was critically understaffed and had to rely on the dregs of the French civil service.
Fifteen thousand Chadian soldiers fought for Free France during WWII and after the war ended, France granted Chad the status of overseas territory and its inhabitants the right to elect representatives to both the French National Assembly, and to a Chadian assembly. Chad was granted independence on August 11, 1960 with the PPT's leader, François Tombalbaye, as its first president. Two years later, Tombalbaye banned opposition parties and established a one-party system. In 1965 Muslims began a civil war. Tombalbaye was overthrown and killed in 1975, but the insurgency continued. In 1979 the rebel factions conquered the capital, and all central authority in the country collapsed. The disintegration of Chad caused the collapse of France's position in the country, and a civil war in which the Libyans unsuccessfully became involved.
A semblance of peace was finally restored in 1990. The government eventually drafted a democratic constitution, and held flawed presidential elections in 1996 and 2001. In 1998, a rebellion broke out in northern Chad, which sporadically flares up despite several peace agreements between the government and the rebels. In 2005 new rebel groups emerged in western Sudan and have made probing attacks into eastern Chad. Power remains in the hands of an ethnic minority. In June 2005, President Idriss Deby held a referendum successfully removing constitutional term limits. In February 2008, an attempted coup rocked the capital.