In the early 20th century, shipping between British India and British Burma rapidly increased. Rangoon became one of the world's busiest ports for immigrant arrivals, ranking alongside New York City. In Rangoon, thousands of Indian migrants arrived to settle in British Burma. The migration fostered strong economic links between India and Burma. British Burma's petroleum industry supplied much of India's petroleum demand. However, commercial links were disrupted during World War II, when Burma came under Japanese occupation. The Japanese took control of the Andaman Islands and used them as a penal colony. After the partition of India in 1947 and Burma's independence in 1948, there was a decline in Indo-Burmese commerce.