Qajar or Safavid Homosexual Painting

Men engaging in anal sex, 
Materials and technique: Gouache on paper 

These two paintings are possibly from Safavid period (1501-1736), although it is more likely that they was created during Qajar period (1794-1925).
نقاشی دو مرد همجنسگرای صفوی یا قاجاری - گالری دانشگاه ایندیانا - بنیاد کنزی - مؤسسهٔ پژوهشی سکس، جنسیت و  تولیدمثل 
These images have been painted in an archaizing Safavid style. Usually, Qajar artists associated erotic scenes with the Safavid period. According to the museum's website, "The gold-painted accents, facial features, Chinese-inspired rolling clouds and the use of colored papers are all indications of the Safavid painting tradition. However, it is thought that it is likely that this work dates from the later Qajar period. The reason, apparently, according to the museum is that many erotic images were intentionally painted this way in hopes of attracting foreign collectors into paying more for its perceived antiquity. 

source: Kinsey Institute Gallery,  [1]
A fun reading about sexuality in Iran, by Shahrnush Parsipur [2] in Persian

From Eros in Asia: Erotic Art from Iran to Japan [3
The kinsey Institute showcases extensive collection of erotic artwork from the Asian continent. It is a must see, and I recommend it to everyone in case you pass by the city of Bloomington, Indiana, USA.

Origins of The Kinsey Institute lie in the scientific research of Indiana University professor and entomologist turned sexuality researcher, Dr. Alfred Kinsey. The Kinsey Institute for Research in Sex, Gender, and Reproduction, or simply The Kinsey Institute, is a nonprofit research institute at Indiana University. It was established in Bloomington, Indiana in 1947. The institute’s mission is to advance sexual health and knowledge worldwide. Research, graduate training, information services, and the collection and preservation of library, art, and archival materials are main activities carried out by The Kinsey Institute. The Institute and Kinsey himself have been the subject of much controversy, initially for engaging in open discussion of sexuality. - Wikipedia, [4], [5

There is also a Hollywood biographical film, written and directed by Bill Condon, about Dr. Alfred Kinsey staring Liam Neeson. Youtube [6]