The sea allowed them to lend themselves out to other countries/groups as soldiers also it helped their economy. Is that all you need?
The total land space of the Japanese islands is about 142,000 square miles<span>. As you can see from map 2 and map 3, it is a very small country when compared with the vast Asian mainland, or with the United States, where it is smaller than the single, although large, state of California.</span>
