Since the topic of your question falls under "Bible", the first clear mention of polygamy in The Bible is; Genesis 4:19 And Lamech took unto him two wives: the name of the one was Adah, and the name of the other Zillah.
Polygamy is as old as humankind and continues to this day.
Polygamy - 1936 was released on: USA: 15 November 1936
Cubism started about 1907/1908 and lasted until 1911.
It started on 7th September 1940 and ended in May 1941.
it started in 1324 and ended in 1584
Its not polygamy if you are not married you would just have a variety of dates or girl/boyfriends. Or if you have a wife and are going out with another women it is not polygamy it is called having an AFFAIR!!!
it started may 10 and ended June 21.
1955 to 30 April 1975.
December 1956 - April 30, 1975
Breaking Polygamy - 2012 TV was released on: USA: 21 November 2012
Primetime What Would You Do - 2009 Polygamy was released on: USA: 17 March 2009
It couldhave started in the b.c period and loyal people keeping concubines.
20 20 - 1978 Breaking Polygamy was released on: USA: 23 November 2012