Thiès (tyĕs) [key], city (1988 pop. 175,465), W Senegal, on the Dakar-Niger RR. It is the trade center for a farming region where peanuts, cassava, and livestock are raised. Manufactures include construction materials, wood furniture and plywood, and textiles. Aluminum phosphate is mined nearby and processed in Thiès. The city was captured in 1862 by the French, who established a military post there in 1864.