Polyandry

Polyandry is a term for when a woman has a relationship or marriage with multiple men. This could be due to culture or religious beliefs, but it is not required. Polyandry is the least common in cultures when compared to monogamy, and polygyny. The most well known examples are societies in the Himalayan mountains and surrounding areas. Polyandry is illegal in many Western countries.

It is in contrast to polygyny.

History
Of the 1,231 societies listed in the 1980 Ethnographic Atlas, 186 were found to be monogamous; 453 had occasional polygyny; 588 had more frequent polygyny; and four had polyandry. Polyandry is less rare than this figure suggests, as it considered only those examples found in the Himalayan mountains (28 societies). More recent studies have found more than 50 other societies practicing polyandry.

Flag
The polyandry flag was coined by Deviantart user NonMonoPrideFlags on December 3rd, 2015.

Resources
https://en.wikipedia.org/wiki/Polyandry