"Native Americans, during the transitional period of Africans becoming the primary race enslaved, were enslaved at the same time and shared a common experience of enslavement. They worked together, lived together in communal quarters, produced collective recipes for food, shared herbal remedies, myths and legends, and in the end they intermarried." Because of a shortage of men due to warfare, many tribes encouraged marriage between the two groups, to create stronger, healthier children from the unions. However, Europeans considered both races inferior and made efforts to make both Native Americans and Africans enemies. Because of European fears of a unified revolt of Native Americans and African Americans, the colonists encouraged hostility between the ethnic groups: "Whites sought to convince Native Americans that African Americans worked against their best interests." In 1751, South Carolina law stated:  "The carrying of Negroes among the Indians has all along been thought detrimental, as an intimacy ought to be avoided." Sometimes Native Americans resented the presence of African Americans. The "Catawaba tribe in 1752 showed great anger and bitter resentment when an African American came among them as a trader." To gain favor with Europeans, the Cherokee exhibited the strongest color-prejudice of all Native Americans. Native Americans were rewarded if they returned escaped slaves, and African-Americans were rewarded for fighting in the late 19th-century Indian Wars. African slaves replaced Native American enslavement and eventually many Native Americans were forced off their land and forced to move westward. There are many examples of this forced removal, but one of the most famous was the Trail of Tears (1830s and 1840s) that forced people of the Cherokee nation and other tribes to move westward to present-day Oklahoma. There are conflicting theories as to what caused the shift between traditional Native American servitude, to the oppressive racialized enslavement adopted by the Five Civilized tribes. One theory is the civilized tribes adopted slavery as means to defend themselves from federal pressure, believing that it would help them maintain their southern lands. In this effort to avoid removal, some Native American tribes attempted to assimilate into white European society through strategies such as formal schooling, adopting Christianity, moving off the reservation, or even owning slaves. They were the most receptive to white pressures to adopt European cultures. In the nineteenth century, European Americans began to migrate west from the coastal areas, and encroach on tribal lands, sometimes in violation of existing treaties. Bands along the frontier, in closer contact with traders and settlers, tended to become more assimilated, often led by chiefs who believed they needed to change to accommodate a new society; indeed, some chiefs were mixed-race and were related to elected American officials.