What was happening during the Renaissance Period that relates to Shakespeare's play Romeo and Juliet?

As William Shakespeare's play Romeo and Juliet is set during the Italian Renaissance, just about everything that happened during this time period has to do with the play! More specifically, the play focuses on two young lovers who come from families who hate one another. The Italian nobility of the Renaissance were constantly caught up in feuds with one another, and Shakespeare has used this fact to create an all-the-more dramatic love story! 

The noble families of Italy were both wealthy and powerful. An unfortunate consequence of using one's wealth and power to make changes in society was that you might upset someone just as wealthy and powerful as you! Members of noble families often brawled in public as displays of domination and defending one's honor. We see this all throughout Romeo and Juliet, as the young men of the Montague and Capulet families engaged in public fights.

Shakespeare never really tells us why the Montagues and Capulets are feuding. It is possible that their grudge is so old that nobody living remembers why the fighting began. Alternately, perhaps it is a hate which began with a small offense and escalated through greater action into the murderous state which sets the social backdrop of the play. Feuding could begin for any number of reasons-- political, financial, social-- and often carried on for so many generations that the families forgot why they started fighting and simply carried on out of habit.