Questions: Prior to 1870, what was a requirement for naturalization?

The answer is Whiteness.

Literacy was not a requirement for naturalization prior to 1870. Literacy tests became more prominent in the early 20th century as part of immigration restrictions, but they were not a factor in the naturalization process before 1870.

Marriage was not a requirement for naturalization. While marriage to a U.S. citizen could influence the naturalization process, it was not a formal requirement for becoming a naturalized citizen.

There was no requirement for ten years of labor for naturalization. The naturalization process did not include a labor requirement of this nature.

The Naturalization Act of 1790 limited naturalization to "free white persons" of "good moral character." This racial requirement was a significant aspect of U.S. naturalization law until it was modified in the mid-20th century. The requirement for "whiteness" was indeed a condition for naturalization prior to 1870.