Interesting. My husband’s Eastern TN ancestors include a Cherokee great-grandmama.
An even bigger driver was the high country's shortage of marriageable women and the Cherokee viewing such marriages as a way to accommodate a growing number of white immigrants and ensure survival of the tribe. Many actually betrothed their children at a young age to children of influential white families, as in my mother's Georgia ancestor's case.
The children, of course, didn't actually get married until they reached the mature old age of 13, 14, 15 or so.
The Cherokee weren't the old tribe which did this, just one of the more successful. Others, such as the Lenape, kidnapped white children outright and impressed them into the tribe. Many didn't want to go back when rescued, particularly when years had passed. Those which didn't make the transition were still good for ransom income, especially in the southwest where Mexican half-breeds would pay good money and/or trade goods on the spot and take them to towns such as Sante Fe where they could turn a quick profit.
Still others, such as the Sioux and Cheyenne, targeted older kids, mid to preteens. They would bribe them away with a pony, comely maiden or sometimes just the promise to lead a life easier than the tough work of farming, ranching or even driving in a wagon train. This happened to my father's great grandfather.