rovided further, That nothing in this act contained shall construed to impair the rights of person or property now pertaining the Indians in said Territory' so long as such rights shall remain unextinguished by treaty between the United States and such Indians, or include any territory which, by treaty with any Indian tribe, is not, without the consent of said tribe, to be included within the territorial line or jurisdiction of any State or Territory; but all such territory shall excepted out of the boundaries, and constitute no part of the Territory of Nebraska, until said tribe shall signify their assent to the President of the United States to be included within the said Territory of Nebraska. or to affect the authority of the government of the United States make any regulations respecting such Indians, their lands, property, or other rights, by treaty, law, or otherwise, which it would have been competent to the government to make if this act had never passed.