Although the details are murky and lost in time, the ancient tribes of Israel practiced monogamy for centuries BCE.
What is fairly certain is that the lost tribes of Israel (who disappeared from the history books) practiced polygamy, thus miring themselves in sexual violence, the endless expelling of low status young males, rotting of the gene pool, sloth, and the increasing need for rigid control over the young girls.
Christianity is credited with spreading monogamy across the Western world, with it, diligence, self discipline, life long commitment to children, and attention to something besides sex.
The evidence is murky, but the case can be made that as monogamy spread across the world, slavery disappeared in 100 to 400 years.
Indeed, the entire polygamous world was engaged in various forms of slavery, and some of the polygamous world is still engaged in slavery in the 21st Century!
Did monogamy help end slavery? Along with the peasants and commoners of inherited elites. There are mountains of evidence that support this.