When a king died, his successor would order that a bronze head be made of his predecessor. Approximately 170 of these sculptures exist, and the oldest date from the twelfth century. The oba, or king, monopolized the materials that were most difficult to obtain, such as gold, elephant tusks, and bronze. These kings made possible the creation of the splendid Benin bronzes; thus, the royal courts contributed substantially to the development of sub-Saharan art. In 1939, heads very similar to those of the Kingdom of Benin were discovered in Ife, the holy city of the Yoruba, which dated to the fourteenth and fifteenth centuries. This discovery supported an earlier tradition holding that it was artists from Ife who had taught Benin the techniques of bronze metalworking. Recognition of the antiquity of the technology in Benin advanced when these sculptures were dated definitively to that era. European interest and the Benin Expedition of 1897 Few examples of African art had been collected by Europeans prior to the nineteenth century, though European printed books already included images of Benin City and of the oba's palace from the early 1600s onward. Only at the beginning of the nineteenth century, when colonization and missionary activity began, did larger numbers of African works begin to be taken to Europe, where they were described as simple curiosities of "pagan" cults. This attitude changed after the Benin Expedition of 1897. In 1897, the vice consul general James Robert Phillips, of the Niger Coast Protectorate, together with six other British officials, two businessmen, translators, and 215 porters, set off toward Benin from the small port of Sapele, Nigeria, The true intention of the visit is disputed. The delegation's stated aim was to negotiate with the Oba of Benin, while some historians contend that it was a reconnaissance mission disguised as a peaceful diplomatic delegation with the goal of ultimately overthrowing the king (Oba) of Benin. Although they had given word of their intended visit, they were later informed that their journey must be delayed, because no foreigner could enter the city while rituals were being conducted; however, the travellers ignored the warning and continued on their expedition. They were ambushed at the south of the city by Oba warriors, and only two Europeans survived the ensuing massacre. News of the incident reached London eight days later and a naval punitive expedition was organized immediately, which was to be