Dalera was an Ancient who was banished from her people for taking a Human as a mate. She lived on a planet, that was named after her by the native Human population, and constructed an elaborate EM based defense system, known as the Shield of Dalera, to protect the planet from the Wraith. Her children and her children's children would be charged with continuing her work to protect the people and would become known as the Chosen for their ancestry allowed them access to Ancient technology because of the Ancient Technology Activation gene.
When AR-1 initially arrived on the planet, seeing their use of Ancient technology prompted one of the locals to assume that Teyla was Dalera returned to them, but the team were able to quickly correct that assumption. (SGA: "The Chosen")