Lost Isa

The Gibberlings' search for their lost homeland Isa yielded nothing. Isa is considered lost, and this people began to settle in the Frozen Frontier near the Kanian Archipelago and on the allod Ingos under the auspices of Kania. Isa is considered destroyed.
However, can it be that this allod actually survived? Why, then, was it never found? Or perhaps it was, but the circumstances of this discovery were carefully concealed from everyone? What happened to Isa?