The French established an opium franchise to put their new colony on a paying basis only six months after they annexed Saigon in 1862. Opium was imported from India, taxed at 10 percent of value, and sold by licensed Chinese merchants to all comers. Opium became an extremely lucrative source of income, and this successful experiment was repeated as the French acquired other areas in Indochina. Shortly after the French established a protectorate over Cambodia (1863) and central Vietnam (1883), and annexed Tonkin (northern Vietnam, 1884) and Laos (1893), they founded autonomous opium monopolies to finance the heavy initial expenses of colonial rule.