 Complete the following phrase:  The trade was not without danger: marauding wakō pirates continued to menace shipping, peaking in the 1550s. The Ningbo Incident occurred in 1523, and from the 1510s, the Portuguese were a new presence. Nevertheless, it was not until the fall of the Ōuchi clan, who by this time had effectively monopolized the missions, in the middle of the sixteenth century, that this pattern would be finally broken. The 1547 mission, returning in 1549, was the last to be accommodated by the Ming authorities. As per The Cambridge History of Japan, by the middle of the sixteenth century, political conditions in Japan had become so chaotic that there was indeed good reason to question the legitimacy of embassies arriving from that country. Two further dates help frame that of the Japan-Ming trade ship flag: 1567, when the Ming rescinded their maritime prohibitions, and 1592, when Toyotomi Hideyoshi launched his initial 