Uh... yeah... show me evidence of these exclusively homosexual societies... because apparently the gheys have not been told.
In order for a "gay civilization" to arise, you'd need the gays to reproduce long enough to develop culture, government, and defense systems. In reproducing at all, you've deemed them "bisexual" and therefore exempt from the example. Did they reproduce via budding? O_o; Or did six or seven queers just run off into the desert together, build a few hut, compose some poetry, poke the heteros with sticks and that's our "society"?
And the term "homosexual" (literally "same" "sex"), depending on its use, implies no exclusivity of homosexual behaviors. You're using it in it's modern tv/pulpit sense (ie. the sexual orientation "homosexual").
homosexuality - Definitions from Dictionary.com
I have used it correctly. My Japanese history book includes 58 references to "homosexuality" in it's appendix...