Morgen Richmond, who is really an ace researcher (not an Ace researcher, but an extremely good one) has dug up the University of Pennsylvania’s old diversity filings.
Now, before 1992, they didn’t list Native Americans as their own category. See, for example, 1990’s report, listing White, Black, Hispanic and Asian hires.
But now in 1992, Penn either hires a Native American female, or discovers it already had one. Or, perhaps, the EEOC had changed its reporting to ask about Native Americans.