The first Jedi Temple was an ancient building established and maintained by the Jedi Order on Ahch-To. It was the first of many temples built throughout the galaxy, and one of the few that were not demolished by the Galactic Empire. Luke Skywalker came to live near the temple as a hermit after his apprentice and nephew Ben Solo turned to the dark side of the Force and destroyed his new generation of Jedi.
The Knights of Ren was a group of dark side users that operated under the command of Snoke, the Supreme Leader of the First Order. Kylo Ren was the head of the organization.
The Caretakers were female Lanai who lived on Ahch-To and attended to the ancient Jedi village on the planet, which housed the first Jedi Temple. They considered it their religious duty to maintain the temple island’s ancient structures and to provide care for those who travelled to their isolated world seeking truth. They led simple, unassuming lives and wore white robes with matching headdresses. The Caretakers were led by their matron, Alcida-Auka.