Ieyasu's biggest accomplishment was unifying Japan. In 1600 Ieyasu defeated his rivals and brought unification to Japan. In 1603 he became the sole leader of Japan and was a very successful leader. He was the first Japanese leader to interact with European explorers and handled it well.
Application of G.R.A.P.E.S : Geography
Since Tokugawa Ieyasu was the sole leader of Japan, when explorers from Portugal arrived he was quickly alerted. For the most part he handled the situation well. The Portugal explorers had guns that the Japanese wanted to buy, but they also spread Christianity which made Ieyasu upset and he tried to stop it.
Was His Impact More Positive or Negative?
Religion was very important to Ieyasu because he tried to stop the spread of Christianity. When the explorers from Portugal tried to spread Christianity and started turning the Japanese people to Christians, Ieyasu got mad. Ieyasu banned Christianity, but Christianity kept spreading and his efforts to ban it ceased.
Geography obviously was extremely important in the Portugal explorers coming to Japan. In fact, the explorers found Japan on accident when the washed up on the shore. Without the current to drag the explorers to the shore, they would have never found Japan.
Ieyasu had a positive affect on the new age of trade in Japan. Yes, he made a mistake by trying to ban Christianity, but he did not do anything cruel to enforce it and soon released the ban. He helped the Japanese economy and gave a good image of Japan to the Europeans.