How to display multiple timelines vertically?

On my website, I need a format that can handle a timeline of a (fictional) history of enormous size conveniently. I already split up the entire timeline into separate pages for eras - that might be another question, but anyways, it was the best solution for me.

Now there's something that never lets me calm down.

Every era depicts events of multiple regions or races, and I think, it can be transparent only if all are shown altogether.

I dropped the idea of horizontal timeline immediately, as my website is built on an engine (Wikidot) and scrolling horizontally within it would be a nightmare.

On the other hand, vertical timeline seems to be extremely crowded, at least the way I implemented it.

I created spreadsheets in MS Excel and imported those to the site. This is how these look like:

Another example:

(ignore colors for now, they are beta)

Is it an acceptable solution, or is there something better on the outside? If there is, ho can I improve it?