Which among the following factors played an important role in India’s trade with China?

Indian rulers, particularly the Pala and Sena rulers of Bengal and the Pallava and Chola rulers of south India, tried to encourage trade with China. The Chola ruler Rajendra I sent a naval expedition against Malaya and the neighbouring countries to overcome their interference in the trade with China. There is evidence to show that there were many shipyards in south India, Orissa and Bengal engaged in the construction of ships. Such shipyards were also located on the west coast, including Gujarat. Thus the growth of India's foreign trade in the area was based on a strong naval tradition, including ship building and a strong navy, and the skill and enterprise of its traders. The Chinese trade was very favourable to the countries engaged in it, so much so that in the thirteenth century the Chinese government tried to restrict the export of gold and silver from China. Indian ships gradually gave way to the Arabs and the Chinese, whose ships were bigger and faster. We are told that the Chinese ships were several storeys high and carried 600 passengers apart from 400 soldiers. An important factor in the growth of the Chinese ships was the use of a primitive mariner's compass, an invention which later travelled from China to the West.