In the 19th century Casablanca became a major supplier of wool to the booming textile industry in Britain and shipping traffic increased (the British, in return, began importing Morocco's now famous national drink, gunpowder tea). By the 1860s, there were around 5,000 residents, and the population grew to around 10,000 by the late 1880s.[7] Casablanca remained a modestly sized port, with a population reaching around 12,000 within a few years of the French conquest and arrival of French colonialists in the town, at first administrators within a sovereign sultanate, in 1906. By 1921, this was to rise to 110,000,[7] largely through the development of bidonvilles