I started John Boswell's Same-Sex Unions in Premodern Europe.
In my latest reading, Boswell argues that there were same-sex unions in
the Greco-Roman world. There was heterosexual matrimony, of course, and
that pertained to such issues as property. But, according to Boswell,
there were also lifelong same-sex unions, and some of those even
occurred when one of the partners was in a heterosexual marriage.
In this post, I'll quote something that Boswell says on page xxvi:
"Many
cultures other than Western ones have recognized and institutionalized
same-sex unions----Japanese warriors in early modern times, Chinese men
and women under the Yuan and Ming dynasties, Native Americans from a
number of tribes (mostly before white domination), many African tribes
well into the twentieth century, and residents (both male and female) of
the Middle East, South-East Asia, Russia, other parts of Asia, and
South America."
Boswell provides footnotes for these claims. This
passage stood out to me because it's relevant to the question of the
extent to which cultures around the world have accepted homosexuality.