Songfacts®:

• Inspired by the breakup of The Marias founders María Zardoya and Josh Conway, "Sienna" imagines the life of a child they never had.
• The song traces a bittersweet alternate reality, a life where love endured, where the couple built a life together, and perhaps had a daughter named Sienna with qualities drawn from both parents: free-spirited, sensitive, and imaginative.
  
  "Sienna would have acted like you, she would have jumped in the pool just like you, and she would have sang to all her pets like I do... but because we broke up, Sienna will never exist," Zardoya lamented to Variety. "And so at the very end where I sing, 'See her face in the forest, then it disappears,' it's like seeing the future you wanted just completely vanish."
• Why Sienna? On the Zach Sang Show, María said the choice was purely her own: "I was like, but if I did have a child with this person, I would name her Sienna."
  
  It wasn't a jointly agreed-upon name, just a quiet, private thought that became the seed for the song.
• The track is the closing song of The Marias' second album, Submarine, whose emotional narrative arc was shaped by Zardoya and Conway's personal breakup. If "No One Noticed" was the soundtrack to quietly navigating heartbreak, "Sienna" is its quiet, almost spectral cousin: a meditation on futures imagined and then lost.
• The Marias performed the song on Jimmy Kimmel Live!. María Zardoya was joined by a young girl representing Sienna, with nine additional children providing ethereal backing harmonies in a smoke-filled, almost dreamlike staging.
• The Jimmy Kimmel performance gave the song a push onto the charts, debuting at #77 on the Billboard Hot 100 for September 20, 2025, over 15 months after it first appeared on their Submarine album.