Eregion is south of Rivendell and the Trollshaws. You can reach the new area through Tal Bruinen or Giant Valley. Eregion has 4 settlements: Gwingris and Mirobel in the North and South West, respectively; Echad Eregion, just West of the map’s center; and East and slightly South of Echad Eregion is Echad Dunann. Just East of there is a gate where you can talk to a dwarf called Rathwald and start Volume 2 of the Epic Books (you did already do the Prologue in Rivendell right? It’s been out since Book 14).
As you work through these rather short and entirely soloable quests, you will be offered Expedition Quests. These will be booted from your quest log upon completion of Chapter 8 of the main path, so you have to do them first if you want to do them at all. The loot isn’t that great, but remember, you’re getting XP again now. More importantly, completing all of the Expedition Quests, and they aren’t hard or out of the way or requiring a Fellowship or such, unlocks a special session play instance: The Fall of Moria. I don’t want to ruin any surprises, but you meet some A-List Middle-Earth VIPs, and the graphics in there alone are worth seeing.