Question about trolls

Hey everyone, I am pretty new to WoW and wanted to learn more. I recently became interested in trolls and wanted to learn some basic facts about them. Mainly, I am curious about Zandalari and Darkspears. I wanted to learn about the lore and also about the troll populations for each group. So, as far as I remember, Zandalari are the most populous and have an actual empire. Then, from there, what would be the order of populated troll groups?
Also, from what I currently understand, Zandalari tend to be more "modern" than other troll groups, but I could be mistaken. Please educate me, I would love to be certain.