My guess is that the early usage of
Kyra /
Kira in the Anglo-Saxon world was Russian influenced, as a feminization of Kyrill, among immigrants.
Based on Wikipedia, the first internationally notable women with this name in the anglo-saxo world were women born in the 1910s, like Grand Duchess
Kira of Russia,
Kyra Petrovskaya
Wayne, and
Kyra Vayne, who may have popularized the name in the mid-20th century.
My guess is that the rise in popularity of this name in the 1960s was above-all influenced by the popularity of similar-sounding names like
Carol,
Karen,
Carla,
Carrie,
Kara, and
Kerry. I wouldn't be surprised if US baby name books gave Kyra/Kira an Irish etymology (connecting it to
Ciara), thus promoting the name among Irish-Americans. (For example, in the prominent
Kennedy family you find names like
Kerry,
Kara, and
Kyra).
Celebrities born in the second-half of the century helped popularise the name further, as you mention.
Conclusion: early usage in the US was Russian-influenced, later usage was inspired by
Ciara and above all by similar sounding names, and eventually by celebrities.
This message was edited 3/13/2022, 3:33 AM