For all of Disneyland’s history, live entertainment has been an important part of the guest experience. From the Pearly Band in Fantasyland to the 5 and Dime on Buena Vista Street, various musical groups perform every day, all over the resort. In the late 1960s, one popular group was called The Kids of the Kingdom.
 Source: Disney Wiki
These performers were not actually kids, but young adult singers and dancers. They primarily performed on the Tomorrowland stage, but would travel around the park for different events. In 1968, Buena Vista Records released an album of the band’s music, which included covers of Disney and other popular songs.
 Source: Gorillas Don’t Blog
The Kids of the Kingdom made their television debut in 1970, performing on The Wonderful World of Disney alongside Kurt Russell, the Osmond Brothers, and Disney’s own Dapper Dans to promote the Haunted Mansion. The band continued to perform on and off in the park until the mid 80s, with some sources dating their final performance at 1986.
Though you can’t see the band perform at Disneyland anymore, their music is still available – especially on YouTube. Feel free to listen and imagine what visiting the park was like during the 60s and 70s!