Phrynian

The Phrynians were the humanoid inhabitants of Phryne. They served as the archivists for the histories, treasures and artifacts of a hundred planets. To protect this knowledge, they hid their solar system (but not their world's own moon) behind an invisibility shield. After the Daleks discovered the moon, they figured out how to pierce the shield and invade the planet. When the Phrynians' defences proved little match for the Daleks, they took refuge in the mountains, planning to rebuild their weapons and fight again another day. (TV21: The Archives of Phryne)