When the author of the citizenship clause (Senator Jacob Howard) introduced his amendment to the Senate he had this to say about the intent of the amendment: "that every person born within the limits of the United States, and subject to their jurisdiction, is by virtue of natural law and national law a citizen of the United States. This will not, of course, include persons born in the United States who are foreigners, aliens, who belong to the families of ambassadors or foreign ministers accredited to the government of the United States, but will include every other class of persons.
The phrase "and subject to their jurisdiction" precluded citizenship for Indians.
The phrase "but will include every other class of persons" bestowed citizenship to Negros.
He lists three classes of persons who do not acquire citizenship by being born in the United States" 1. foreigners, 2. aliens, 3. members of families of foreign diplomats.
See the Congressional Globe for the 1st session of the 39th Congress, page 2890 for the Senate's discussion of the amendment.