Taru's built a wall to keep yags out but no one complains about that!!
This is not even a remotely good analogy. Want a list?
Windurstian immigrants are mithra, not yagudo.
Taru were originally the aggressors in Saruta, yagudo were kicked out.
Yagudo went to war with Windurst because they were threatened to(Tzee Xicu didn't want to).
Fort Karugo-Narugo is not a wall but...you know, a fort and it was built because Windurst was at war with their neighbours.
Tell me a single one of these things that is anywhere near the situation of America(Windurst) with Mexico(yags).