O lord, Janaka was the king of Videha and his daughter was Sita. Tvashtri himself created her wishing to make her the beloved queen of Rama.
विदेहराजो जनकः सीता तस्यात्मजा विभो। यां चकार स्वयं त्वष्टा रामस्य महिषीं प्रियाम्॥