The few archaeological investigations in the Yurok area indicate Yurok presence there in late prehistoric times. There was no known historic contact between the Yurok and Europeans prior to 1775, when they were visited by the Spanish. Fur traders from the Hudson's Bay Company ventured into the Yurok area in 1827, and gold rush prospectors entered the lower Klamath River area in 1850-1851. The first Anglo-European settlement began around 1852. There was considerable violence between the Yurok and the gold seekers during this era. After 1855, however, the Yurok were protected by military and government officials in the area. Prior to the advent of Europeans, the Yurok interacted primarily with the Hupa and the Karok, who shared a common northwestern California coast lifestyle. On their periphery, there were Contacts with other groups, including the Wiyot, Chilula, Chimariko, Shasta, Tututni, Chetco, and Tolowa. There were extensive kinship and economic ties between the Yurok and their neighbors, yet the Yurok, Hupa, and Karok were fiercely territorial. They would visit one another's villages for ceremonies, but were generally self-sufficient within their territories, except for obsidian and dentalium shell that were obtained through trade. The Yurok were obsessed with amassing and holding wealth and often sued or demanded tribute from other Yuroks or their neighbors for a variety of infractions. Feuds were fought between Yurok villages, and the Yuroks waged wars, albeit small-scale ones, with the Hupa, Chilula, and Tolowa. Tribute was often extracted by the Yurok, but there was also a complex system of compensation for damages inflicted in feuds between Yurok families or villages. Compensation was usually in the form of strings of dentalium shell used by the Yurok as a measure of currency and wealth.