Well Southeast Asia has lots of islands. So Many ships have to pass from southeast Asia. Many Chinese and Japanese goods go across southeast Asia to Reach Europe. So many of the Southeast Asian countries take advantage of the trade and built many ports. And It helps their economy grow. Just look at Singapore. Singapore is a country the size of one city. But since it location(south east asia) It more of a city port and it one of the wealthiest country in all of Asia.
<span>Sea trade between China and India had to pass through either
the Malacca or Sunda strait; this area commanded the straits thus they
controlled all trade routes. This is the answer</span>
