The Knot. Every little world builds a string- sometimes a stronger, sometimes a rather small and weak one. But, in the very end, all of their stories meet in the Knot.
It is rather hard to find a reason for the role the Knot is playing in the chaos of aorlds an all their different stories, except that, in the year 0 (Pre) Blackbloods entered the world. It is unknown where they came from, but they settled in the Knot. And by Blackbloods being able to open portals to other worlds and this way make world jumping possible, the Knot was created.
I report from about 6 000 years after the Blackbloods entered the Knot. An era has ended by the death of Lilo, who has lived all through the last era. And what I will do, is telling you the story of the last era. Well, certainly an uncountable number of things has happened in 5 000 , so I will thell you some stories of the era "Post".
What you first will have to learn are the countires and military powers of The Knot throughout history and ideally, their role. Once we have done that, you will probably also know a fair amount of characters, so why not concentrate on them? That would be one way of understanding things. Or just read the stories. You could also do that. But don't expect to understand everything. Understanding will come by time.