The Shimazu clan of the Japanese feudal domain of Satsuma invaded the kingdom during the 1609 Invasion of Ryukyu. Satsuma was able to capture Shuri Castle and King Shō Nei by early May, then sent a message to the Sakishima Islands demanding their surrender, which they complied with. In the following centuries of vassalage to Satsuma, the Ryukyuan government was placed under extreme tax pressure, and instituted a heavy poll tax in the Sakishima Islands. As a result of the extreme economic conditions, infanticide and other methods of population control became common, as they did throughout the Ryukyu Islands; remains of the sites where this took place can still be found throughout the Sakishima Islands. Yaeyama islanders were taxed even more heavily than those of Miyako, as the rebel Oyake Akahachi was from Yaeyama. The kingdom prohibited migration of islanders, isolating them to prevent group resistance. The Yaeyama earthquake in 1771 caused a tsunami which killed 12,000, or a half of the entire Sakishima population. Because the soil was adversely affected by salination, famines were frequent, and the population of the islands further decreased until the early Meiji period.