There were a lot of reasons but some of the most important ones were the increasing tension in governing places like the Philippines and Hawaii where there was a huge amount of Japanese citizens, as well as Japan's breach of the open door policies which established that all countries should have equal rights in trading with China.<span />
Thousands of trees were cut down to build the railroad. Western forests were devastated.
The boat is traveling upstream
Ethnicity and religion has been a serious cause of division among the nations of Eastern Europe.