Easteros was an Erfworld Side led by Bell, who owned the Arkenshoes. It was part of a Tribe of green skinned men. It was allied with Westeregg, another Side of the same Tribe, that was led by the Ruler's sister. This alliance fought against el-Efbaum and Haffaton. The Side was destroyed following a casting of the Perfect Warlord Spell.
Real World References
By switching the first two letters in Easteros and Westeregg, the names become Westeros (the main continent of the A Song of Ice and Fire series of books) and Easter Egg (a hidden feature in a video or program). The latter may also be a reference to West Egg, the setting of the novel The Great Gatsby. Whether or not these points will be plot relevant is unknown, but is unlikely due to the destruction of the side.