The best work I have read about football rivalry is " The Soccer Tribe" by the well known anthropologist Desmond Morris.
In fact I have just bought the latest edition for my pals 65th birthday (I have the earlier edition from about 40 years ago).
It describes how football became a truly global sport,loved by people of many nationalities,races and religions.
And it's all down to how humans loved hunting and killing as food for survival.
And when we turned to farming animals,we didn't need to hunt anymore,so we did it for pleasure.
And when we started to live in cities, there wasn't space to hunt anymore,so we brought the animals to the cities,and hunted them in vast arenas.
And when that became unacceptable in the late 19th century,we adopted football as a substitute for hunting,with scoring a goal being the equivalent of a kill, whereby everyone rejoices and celebrates the goal/kill.
An absolutely fascinating book, and one I highly recommend to everyone on BM.
(The latest edition is about £15 on eBay,and the original edition is as little as £5).