Maritime trading between South Asia and European merchants began after the Portuguese explorer Vasco de Gama returned to Europe. British, French, Portuguese colonial interests struck treaties with these rulers and established their trading ports. In northwest South Asia, a large region was consolidated into the Sikh Empire by Ranjit Singh. After the defeat of the Nawab of Bengal and Tipu Sultan and his French allies, the British Empire expanded their interests till the Hindu Kush region. In the east, the Bengal region was split into Muslim East Bengal and Hindu West Bengal, by the colonial British empire, in the early 1900s, a split that was reversed. However, after World War II, at the eve of India's independence, the region was split again into East Pakistan and West Bengal. East Pakistan became Bangladesh in 1971.