Complex sentence: In 1639 Iemitsu officially closed off Japan from the rest of the world, limiting trade to the Chinese and Dutch merchants ensconced on the island of Deshima in Nagasaki and the proxy trade with China carried out by the Ryukyu Kingdom under the control of the Shimazu clan.
Split into simpler sentences: In 1639 Iemitsu officially closed off Japan from the rest of the world. This restrictive edict limiting trade to the Chinese and Dutch merchants ensconced on the island of Deshima in Nagasaki and the proxy trade with China carried out by the Ryukyu Kingdom under the control of the Shimazu clan.