What was the main reason the lords proprietors wanted a large number of people settle in Carolina

First, the Navajo people lived in the southwest of the United States. During the winter of 1863, they were forced to walk around 300 miles to the Fort Sumner in New Mexico, this event is known as the "Long walk". Sadly, the Fort Sumner didn't have the proper accommodations to hold all the population, so the Navajo started to die because of the lack of water, food, livestock and due the attacks from other indigenous groups. Later, in 1868, the surviving Navajos were allowed to return to their territories and to live on a reservation. In this period, the U.S. kept many forts in the Navajo territory and increased the relationship that the government had with this indigenous group. An example is the participation of the Navajo in the education system.  

Second, the Nez Perce Native Americans lived in the Northwest of the actual United States.  Around 1877, the tribe was under pressure from the U.S. who wanted to relocate them into a reservation. The Nez Perce tribe decided to leave their territory and to seek for help from their allies in Canada. This way, during 5 months, the Nez Perce tribe ran away from the U.S. army in order to escape. Unsuccessfully, they suffered great losses on the way and they were captured and forced to surrender when they were only 40 miles away from the Canada border. Afterwards the Nez Perce tribe was relocated in a reservation in Idaho and it lost most of its territory, nowadays 90% of the Nez Perce territory is occupied by white people.

In comparison, you can see that the Navajo didn't fight against the U.S. army when they were relocated and that they were included into the government system in "an easier way". Also, in the present, the Navajo is the most numerous indigenous group in the United States. On the opposite hand, the Nez Perce fought against the U.S. army and lost most of its population, so they didn't integrate as well as the Navajo, which is curious when you see their actual population is still low and many of their traditions are gone.

A similarity between these two groups is that both of them suffered the expropriation of their territories and that the U.S. government promoted activities like mining and railroad building in their reservation without asking them before.