During our research of Chinese Martial Arts in the "military sector", we kept coming up with references to the Japanese sword. As strange as it may seem, Ming period China wanted and indeed, needed, swords from Japan. The historical record shows us that swords and skills were quite readily exchanged.
Little seems to be known about Japanese swords imported to China during the Ming dynasty. The trade was actually far more active than our common perception shows us. These prized weapons were given to specialist units on border defence, and those fighting the pirate raiders on China’s coastline. Below is a summary of tangible, official records. This gives us some idea of the Ming Dynasty trade in purchasing high quality swords for their own military use.
The Eikyô four (Japanese Bakufu name) of 1432, was a trade mission that had loaded 3.000 swords, the Eikyô six (1434) mission also 3.000 swords, the Kyôtoku two (1453) mission 9.968 swords, the Ônin two (1468) about 30.000, the Bunmei eight (1476) mission around 7.000, the Bunmei 15 (1483) mission 38.610, the Meiô two (明応, 1493) and Eishô eight (1511) missions each around 7.000, and the Tenbun eight (天文, 1539) mission 24.152 swords. That makes altogether around 128.000 swords, an average of about 12.800 swords per mission. The very last tribute mission was undertaken in Tenbun 16 (1547) before the system collapsed.
We do not know how many swords, if any, were on that last mission but we know that at least 128 000 swords were officially bought by the Ming Dynasty for military purpose. Experts speculate that the black market trade was far above that number.
What we do not know, is why so few extant swords survive from this period.