Military: War
The returning elves were rejected by the western elves.
After the Scourge of the Elves was defeated, elves who fled east returned, but were viewed as traitors, and were told to leave. But they had nowhere to go, so they stayed, and the western elves attempted to force them to leave. They fought for a year before finally the returners were victorious, but barely. They agreed to remain separate from the other elves, but were allowed to live in the western lands. This led to the "True Westerners" and "False Westerners."