According to her Wikipedia article, she came from Mongolia. Somehow, her father was exiled from Russia in 1814 and the family drifted around Europe before finally settling in France. After her father's possible involvement in burning Moscow to deny it to Napoléon, she converted to Catolicism and married the Count of Ségur. At the age of 58, she wrote her first novel, "Un bon petit diable," in 1857. Fourteen more are listed in her Wikipedia article.