SeasonIII

In early October 2004, series of scenario began with Orc Invasion and end with Discovery of New Empire, introduction of UO:SE.
EMs served their own shards in official scenario though, it's clear that they became more active in shard individual inventive events than Season II. So, official shard common items and original shard specific items were created in each shard. t'was Tough season for me.
EM events became less frequent before Season IV
One remarkable thing, Korean shards began to produce their own event items by Korean GM team. They have had events relatively continuously from the start in Autumn 2004 untill the team got shut down.
Go see more detail in "Backgrounds" in Introduction if you like.