The article Moche Sex Pots: Reproduction and Temporality in Ancient South America has a lot of information about this civilization.
The first surprise is what is and is not represented. While sodomy, masturbation, and fellatio are frequently depicted, penile penetration of the vagina is so rare that some authors mistakenly assume the act was never represented at all. The most common sexual position shown is anal sex, which is reproduced over and over, in a variety of styles, indicating that it was produced in many different workshops over a long period of time.
Researchers were even confused, thinking it depicted only homosexuality:
The similarity of the two figures in the anal sex scenes, in addition to the close association in contemporary minds between sodomy and male homosexuality, has led some writers to erroneously assume that these couples are two men, but most pots portray a heterosexual pair. Indeed, the artist often carved the genitalia carefully, despite the small scale, so as to demonstrate beyond a doubt that the penetrated figure is female, and that it is the anus, not the vagina,that is being penetrated.
When the european colonists arrived, the Moche civilization was long gone, probably due to severe climatic events between 536 and 594 AD, but anal sex was still a preferred form of sex in the region. The spanish tried to eradicate it:
But early explorers repeatedly refer to the prevalence of anal sex -- both heterosexual and homosexual -- as a preferred sexual practice on the North Coast; in the words of one early observer, the people of the region were "inclined to sodomy." (Spanish abhorrence of sodomy renders these ethnohistoric documents difficult to interpret, but the observed difference between this and other regions is unmistakable, as is the clerical despair at the difficulty in eradicating the practice.)
This reading is very interesting. It's great to know there was a entire anal-sex centered culture. At the same time, it's a shame the colonists imposed their taboos over native people that were otherwise happy with it.
Reference and credit for images section:
Weismantel, Mary. "Moche sex pots: reproduction and temporality in ancient South America." American Anthropologist 106.3 (2004): 495-505.
TURNER, ANDREW D. "SEE ALSO Anā Hiya Anti (2000; Elham Mansour); Bareed Mista3jil: True Stories (2009); Halat Shaghaf (1998; Nihad Sirees); Jannāt wa-Iblīs (1992; Nawal El Saadawi); Lesbanese (2008; Alissar Gazal)." Feminist Studies 38.1 (2012): 17-49.