80's, which restricted all external trade, unofficial trade with Nigeria has resumed. Official trade with France was declined after 1982, primarily because many French-affiliated firms closed during the conflicts (A Country Study). Controlling the smuggling and the black market activity was very difficult. Chad and its neighbors had few resources that could be fully devoted to controlling the border. Collusion between smugglers and border patrols and customs agents were common and made it hard to stop. Chad's unofficial trade with Nigeria, Cameroon, and Central African Republic has historical and social roots. Extended and tribal family connections across the borders have encouraged traders to keep long-distance commercial and financial networks beyond colonial and, later, national government control on taxes. Unofficial imports consisted of petroleum products, consumer goods, !
             such as sugar, cooking oil, soap, and cigarettes, which competed with the production by national industries. Chad also exported 40% of its oil to Exxon, 40% to Sh
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