Prior to the arrival of the Belgians, the Congo region was not claimed by any European power, but was divided into an array of local chiefdoms. Leopold employed explorer Henry Stanley, famous for having crossed the continent from east to west, to serve as his agent in the region. In the name of the Belgian sovereign, Stanley negotiated "treaties" with local leaders, securing, in the minds of the Europeans, legal possession of what Leopold christened the "Congo Free State," which was in point of fact a vast swath of land that he personally owned. At the Berlin Conference of 1884-85 Leopold secured the assent of other European leaders to the disingenuous treaties he had forced on natives, none of whom were literate. He then set out to establish actual, instead of theoretical, dominion over the region, using an army of heavily-armed conscripts to defeat local people who opposed the depredations of Belgian officials. When the market for rubber exploded in the 1890s, Leopold established the brutal labor regime for which he has become infamous. The sad case of the Belgian Congo Free State embodied imperialism for many outside observers, and Leopold, despite his efforts to portray himself as a humanitarian, quickly became a symbol of European greed and brutality.