There were many economy reasons for expanding. When you have more land you profit more. There would also more opportunity with more land.
It is b i think the ellis island
B. It was to aid Europe after WWII
Answer:
Edit
The Mongol invasions of Japan (元寇 Genkō), which took place in 1274 and 1281, were major military efforts undertaken by Kublai Khan to conquer the Japanese archipelago after the submission of Goryeo (Korea) to vassaldom. Ultimately a failure, the invasion attempts are of macro-historical importance because they set a limit on Mongol expansion and rank as nation-defining events in the history of Japan.
