Welcome back! Depending on how long it’s been since you were last active, you may notice a couple unexpected changes. The most prominent one is that Herod has been connected to 7 other Classic Era realms, all within the PvP East:
These realms are effectively merged as one server, commonly referred to as a ‘cluster’. The bluepost I quoted above lists the other 4 North American clusters, as well as one OCE cluster.
There are free transfers available to the PvP West cluster (Whitemane+9other realms) and the PvE East cluster (Mankrik+4other realms). There are also some select RP realms that were exempted from realm connections. Regardless, all Classic Era realms/clusters in North America queue together for instanced PvP/Battlegrounds.
I myself play horde with my guildmates in the other PvP East cluster (Benediction, Faerlina, Heartseeker, Incendius, and Netherwind). Best of luck and if you have any questions, ask away!