Antibinary (aka anti-binary) is a gender defined as "a gender identity that is in direct opposition to or unaffiliated with the western gender binary." Since the idea of the modern gender binary was created by western settlements, people who are antibinary may feel more connected to the genders that were used by their ancestors, or just feel disconnected to the western idea of a gender binary as a whole. It is an identity that is exclusive for BIPOC or people who are/have been oppressed by white people. People who are two-spirit may fall into this identity as they are identifying with a gender outside of the western gender binary, and instead fit more into the genders that their ancestors used.
Flag
The flag has an unknown creator, but was created to not use any traditionally gendered colors like pink or blue. The colors used are meant to represent being non-gendered as a BIPOC.