From the time of the acquisition of Macau in 1557, and their formal recognition as trade partners by the Chinese, the Portuguese started to regulate trade to Japan, by selling to the highest bidder the annual "Captaincy" to Japan, in effect conferring exclusive trading rights for a single carrack bound for Japan every year. The carracks were very large ships, usually between 1000 and 1500 tons, about double or triple the size of a large galleon or junk.