I would like to know what exactly this sinat chinam looked like. What did they "hate" about each other? I feel like the answer to this would be better if it gave a full picture of the state of the Jewish nation at that time: what they were doing, how they were divided and united, any specific politics going on... stuff like that.
So hence I ask for a historical account, as full and rich as possible. It doesn't have to be contemporary to the times, could be a later traditional historian with enough weight to be included as a source here at Mi Yodeya. It doesn't have to be a historian, as even more ideal would be a work by one of our Chazal at any point in time since then.
Failing all that, a collection of whatever short (or long?) mentions there of these matters in our sources would also be a wonderful answer.
Note: the reason I am asking this is to try to understand the religious ethical and halachic connotations of sinat chinam, as well as understand ahavat Yisrael and ahavat chinam better. There are many essays on these topics, but I would really like to come at this topic from the angle of looking at the zeitgeist of the times directly, in this question.
Also, the idea of Achdut is floating around right now like a pleasant breeze, BH and it would be nice to gather information relevant to that.