Task: Question Answering
Input (English): Passage: Vessels from neighboring East Asian states such as Silla and Balhae of Korea and the Hizen Province of Japan were all involved in the Yellow Sea trade, which Silla dominated. After Silla and Japan reopened renewed hostilities in the late 7th century, most Japanese maritime merchants chose to set sail from Nagasaki towards the mouth of the Huai River, the Yangzi River, and even as far south as the Hangzhou Bay in order to avoid Korean ships in the Yellow Sea. In order to sail back to Japan in 838, the Japanese embassy to China procured nine ships and sixty Korean sailors from the Korean wards of Chuzhou and Lianshui cities along the Huai River. It is also known that Chinese trade ships traveling to Japan set sail from the various ports along the coasts of Zhejiang and Fujian provinces.The Chinese engaged in large-scale production for overseas export by at least the time of the Tang. This was proven by the discovery of the Belitung shipwreck, a silt-preserved shipwrecked Arabian dhow in the Gaspar Strait near Belitung, which had 63,000 pieces of Tang ceramics, silver, and gold (including a Changsha bowl inscribed with a date: "16th day of the seventh month of the second year of the Baoli reign", or 826, roughly confirmed by radiocarbon dating of star anise at the wreck). Beginning in 785, the Chinese began to call regularly at Sufala on the East African coast in order to cut out Arab middlemen, with various contemporary Chinese sources giving detailed descriptions of trade in Africa. The official and geographer Jia Dan (730–805) wrote of two common sea trade routes in his day: one from the coast of the Bohai Sea towards Korea and another from Guangzhou through Malacca towards the Nicobar Islands, Sri Lanka and India, the eastern and northern shores of the Arabian Sea to the Euphrates River. In 863 the Chinese author Duan Chengshi (d. 863) provided a detailed description of the slave trade, ivory trade, and ambergris trade in a country called Bobali, which historians suggest was Berbera in Somalia. In Fustat (old Cairo), Egypt, the fame of Chinese ceramics there led to an enormous demand for Chinese goods; hence Chinese often traveled there (this continued into later periods such as Fatimid Egypt). From this time period, the Arab merchant Shulama once wrote of his admiration for Chinese seafaring junks, but noted that their draft was too deep for them to enter the Euphrates River, which forced them to ferry passengers and cargo in small boats. Shulama also noted that Chinese ships were often very large, with capacities up to 600–700 passengers. 
Question: What was proven by the discovery of the Belitung shipwreck?
Output (English): The Chinese engaged in large-scale production for overseas export.